Abdelrahman Said
3033 lines
142 KiB
HTML
3033 lines
142 KiB
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<link rel="prev" href="igraph-Processes.html" title="Chapter 30. Processes on graphs">
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<link rel="chapter" href="igraph-Installation.html" title="Chapter 2. Installation">
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<link rel="chapter" href="igraph-Basic.html" title="Chapter 4. Basic data types and interface">
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<link rel="chapter" href="igraph-Memory.html" title="Chapter 6. Memory (de)allocation">
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<link rel="chapter" href="igraph-Data-structures.html" title="Chapter 7. Data structure library: vector, matrix, other data types">
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<link rel="chapter" href="igraph-Random.html" title="Chapter 8. Random numbers">
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<link rel="chapter" href="igraph-Iterators.html" title="Chapter 9. Vertex and edge selectors and sequences, iterators">
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<link rel="chapter" href="igraph-Attributes.html" title="Chapter 10. Graph, vertex and edge attributes">
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<link rel="chapter" href="igraph-Generators.html" title="Chapter 11. Deterministic graph generators">
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<link rel="chapter" href="igraph-Games.html" title='Chapter 12. Stochastic graph generators ("games")'>
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<link rel="chapter" href="igraph-Bipartite.html" title="Chapter 13. Bipartite, i.e. two-mode graphs">
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<link rel="chapter" href="igraph-Spatial.html" title="Chapter 14. Spatial graphs">
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<link rel="chapter" href="igraph-Operators.html" title="Chapter 15. Graph operators">
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<link rel="chapter" href="igraph-Visitors.html" title="Chapter 16. Graph visitors">
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<link rel="chapter" href="igraph-Structural.html" title="Chapter 17. Structural properties of graphs">
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<link rel="chapter" href="igraph-Cycles.html" title="Chapter 18. Graph cycles">
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<link rel="chapter" href="igraph-Cliques.html" title="Chapter 19. Cliques and independent vertex sets">
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<link rel="chapter" href="igraph-Motifs.html" title="Chapter 20. Graph motifs, dyad census and triad census">
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<link rel="chapter" href="igraph-Isomorphism.html" title="Chapter 21. Graph isomorphism">
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<link rel="chapter" href="igraph-Coloring.html" title="Chapter 22. Graph coloring">
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<link rel="chapter" href="igraph-Flows.html" title="Chapter 23. Maximum flows, minimum cuts and related measures">
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<link rel="chapter" href="igraph-Separators.html" title="Chapter 24. Vertex separators">
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<link rel="chapter" href="igraph-Community.html" title="Chapter 25. Detecting community structure">
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<link rel="chapter" href="igraph-Graphlets.html" title="Chapter 26. Graphlets">
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<link rel="chapter" href="igraph-HRG.html" title="Chapter 27. Hierarchical random graphs">
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<link rel="chapter" href="igraph-Embedding.html" title="Chapter 28. Embedding of graphs">
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<link rel="chapter" href="igraph-Layout.html" title="Chapter 29. Generating layouts for graph drawing">
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<link rel="chapter" href="igraph-Processes.html" title="Chapter 30. Processes on graphs">
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<link rel="chapter" href="igraph-Foreign.html" title="Chapter 31. Reading and writing graphs from and to files">
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<link rel="chapter" href="igraph-Linalg.html" title="Chapter 32. Using BLAS, LAPACK and ARPACK for igraph matrices and graphs">
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<link rel="chapter" href="igraph-Nongraph.html" title="Chapter 33. Non-graph related functions">
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<link rel="chapter" href="igraph-Advanced.html" title="Chapter 34. Advanced igraph programming">
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<link rel="chapter" href="igraph-Glossary.html" title="Chapter 35. Glossary">
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<link rel="chapter" href="igraph-Licenses.html" title="Chapter 36. Licenses for igraph and this manual">
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<div class="chapter">
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<div class="titlepage"><div><div><h1 class="title">
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<a name="igraph-Foreign"></a>Chapter 31. Reading and writing graphs from and to files</h1></div></div></div>
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<div class="toc"><dl class="toc">
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<dt><span class="section"><a href="igraph-Foreign.html#simple-edge-list-and-similar-formats">1. Simple edge list and similar formats</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#binary-formats">2. Binary formats</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#graphml-format">3. GraphML format</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#gml-format">4. GML format</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#pajek-format">5. Pajek format</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#ucinets-dl-file-format">6. UCINET's DL file format</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#graphviz-format">7. Graphviz format</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#leda-format">8. LEDA format</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#locale-helpers">9. Convenience functions for locale change</a></span></dt>
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</dl></div>
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<p>These functions can write a graph to a file, or read a graph
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from a file.</p>
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<p>They assume that the current locale uses a decimal point and not
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a decimal comma. See <a class="link" href="igraph-Foreign.html#igraph_enter_safelocale" title="9.1. igraph_enter_safelocale — Temporarily set the C locale."><code class="function">igraph_enter_safelocale()</code></a> and
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<a class="link" href="igraph-Foreign.html#igraph_exit_safelocale" title="9.2. igraph_exit_safelocale — Temporarily set the C locale."><code class="function">igraph_exit_safelocale()</code></a> for more information.</p>
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<p>Note that as <span class="command"><strong>igraph</strong></span> uses the traditional C streams, it is
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possible to read/write files from/to memory, at least on GNU
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operating systems supporting <span class="quote">“<span class="quote">non-standard</span>”</span> streams.</p>
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<div class="section">
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
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<a name="simple-edge-list-and-similar-formats"></a>1. Simple edge list and similar formats</h2></div></div></div>
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<div class="toc"><dl class="toc">
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<dt><span class="section"><a href="igraph-Foreign.html#igraph_read_graph_edgelist">1.1. <code class="function">igraph_read_graph_edgelist</code> — Reads an edge list from a file and creates a graph.</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#igraph_write_graph_edgelist">1.2. <code class="function">igraph_write_graph_edgelist</code> — Writes the edge list of a graph to a file.</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#igraph_read_graph_ncol">1.3. <code class="function">igraph_read_graph_ncol</code> — Reads an <code class="literal">.ncol</code> file used by LGL.</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#igraph_write_graph_ncol">1.4. <code class="function">igraph_write_graph_ncol</code> — Writes the graph to a file in <code class="literal">.ncol</code> format.</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#igraph_read_graph_lgl">1.5. <code class="function">igraph_read_graph_lgl</code> — Reads a graph from an <code class="literal">.lgl</code> file.</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#igraph_write_graph_lgl">1.6. <code class="function">igraph_write_graph_lgl</code> — Writes the graph to a file in <code class="literal">.lgl</code> format.</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#igraph_read_graph_dimacs_flow">1.7. <code class="function">igraph_read_graph_dimacs_flow</code> — Read a graph in DIMACS format.</a></span></dt>
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<dt><span class="section"><a href="igraph-Foreign.html#igraph_write_graph_dimacs_flow">1.8. <code class="function">igraph_write_graph_dimacs_flow</code> — Write a graph in DIMACS format.</a></span></dt>
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</dl></div>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="igraph_read_graph_edgelist"></a>1.1. <code class="function">igraph_read_graph_edgelist</code> — Reads an edge list from a file and creates a graph.</h3></div></div></div>
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<a class="indexterm" name="id-1.32.5.2.2"></a><p>
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</p>
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<div class="informalexample"><pre class="programlisting">
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igraph_error_t igraph_read_graph_edgelist(igraph_t *graph, FILE *instream,
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igraph_int_t n, igraph_bool_t directed);
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</pre></div>
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<p>
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</p>
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<p>
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This format is simply a series of an even number of non-negative integers separated by
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whitespace. The integers represent vertex IDs. Placing each edge (i.e. pair of integers)
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on a separate line is not required, but it is recommended for readability.
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Edges of directed graphs are assumed to be in "from, to" order.
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</p>
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<p>
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The largest vertex ID plus one, or the parameter <em class="parameter"><code>n</code></em> determines the vertex count,
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whichever is larger. See <a class="link" href="igraph-Foreign.html#igraph_read_graph_ncol" title="1.3. igraph_read_graph_ncol — Reads an .ncol file used by LGL."><code class="function">igraph_read_graph_ncol()</code></a> for reading files where
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vertices are specified by name instead of by a numerical vertex ID.
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</p>
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<p><b>Arguments: </b>
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</p>
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<div class="variablelist"><table border="0" class="variablelist">
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<colgroup>
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<col align="left" valign="top">
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<col>
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</colgroup>
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<tbody>
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<tr>
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<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
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<td><p>
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Pointer to an uninitialized graph object.
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</p></td>
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</tr>
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<tr>
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<td><p><span class="term"><em class="parameter"><code>instream</code></em>:</span></p></td>
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<td><p>
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Pointer to a stream, it should be readable.
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</p></td>
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</tr>
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<tr>
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<td><p><span class="term"><em class="parameter"><code>n</code></em>:</span></p></td>
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<td><p>
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The number of vertices in the graph. If smaller than the
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largest integer in the file it will be ignored. It is thus
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safe to supply zero here.
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</p></td>
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</tr>
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<tr>
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<td><p><span class="term"><em class="parameter"><code>directed</code></em>:</span></p></td>
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<td><p>
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If true the graph is directed, if false it
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will be undirected.
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</p></td>
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</tr>
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</tbody>
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</table></div>
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<p>
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</p>
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<p><b>Returns: </b></p>
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<div class="variablelist"><table border="0" class="variablelist">
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<colgroup>
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<col align="left" valign="top">
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<col>
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</colgroup>
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<tbody><tr>
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<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
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<td><p>
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Error code:
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<code class="constant">IGRAPH_PARSEERROR</code>: if there is a
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problem reading the file, or the file is syntactically
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incorrect.
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</p></td>
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</tr></tbody>
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</table></div>
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<p>
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Time complexity: O(|V|+|E|), the
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number of vertices plus the number of edges. It is assumed that
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reading an integer requires O(1) time.
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</p>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="igraph_write_graph_edgelist"></a>1.2. <code class="function">igraph_write_graph_edgelist</code> — Writes the edge list of a graph to a file.</h3></div></div></div>
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<a class="indexterm" name="id-1.32.5.3.2"></a><p>
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</p>
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<div class="informalexample"><pre class="programlisting">
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igraph_error_t igraph_write_graph_edgelist(const igraph_t *graph, FILE *outstream);
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</pre></div>
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<p>
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</p>
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<p>
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</p>
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<p>
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Edges are represented as pairs of 0-based vertex indices.
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One edge is written per line, separated by a single space.
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For directed graphs edges are written in from, to order.
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</p>
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<p><b>Arguments: </b>
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</p>
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<div class="variablelist"><table border="0" class="variablelist">
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<colgroup>
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<col align="left" valign="top">
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<col>
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</colgroup>
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<tbody>
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<tr>
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<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
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<td><p>
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The graph object to write.
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</p></td>
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</tr>
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<tr>
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<td><p><span class="term"><em class="parameter"><code>outstream</code></em>:</span></p></td>
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<td><p>
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Pointer to a stream, it should be writable.
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</p></td>
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</tr>
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</tbody>
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</table></div>
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<p>
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</p>
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<p><b>Returns: </b></p>
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<div class="variablelist"><table border="0" class="variablelist">
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<colgroup>
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<col align="left" valign="top">
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<col>
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</colgroup>
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<tbody><tr>
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<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
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<td><p>
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Error code:
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<code class="constant">IGRAPH_EFILE</code> if there is an error writing the
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file.
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</p></td>
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</tr></tbody>
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</table></div>
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<p>
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Time complexity: O(|E|), the
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number of edges in the graph. It is assumed that writing an
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integer to the file requires O(1)
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time.
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</p>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="igraph_read_graph_ncol"></a>1.3. <code class="function">igraph_read_graph_ncol</code> — Reads an <code class="literal">.ncol</code> file used by LGL.</h3></div></div></div>
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<a class="indexterm" name="id-1.32.5.4.2"></a><p>
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</p>
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<div class="informalexample"><pre class="programlisting">
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igraph_error_t igraph_read_graph_ncol(igraph_t *graph, FILE *instream,
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const igraph_strvector_t *predefnames,
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igraph_bool_t names,
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igraph_add_weights_t weights,
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igraph_bool_t directed);
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</pre></div>
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<p>
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</p>
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<p>
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Also useful for creating graphs from <span class="quote">“<span class="quote">named</span>”</span> (and
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optionally weighted) edge lists.
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</p>
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<p>
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This format is used by the Large Graph Layout program
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(<a class="ulink" href="https://lgl.sourceforge.net" target="_top">https://lgl.sourceforge.net</a>), and it is simply a
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symbolic weighted edge list. It is a simple text file with one edge
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per line. An edge is defined by two symbolic vertex names separated
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by whitespace. The vertex names themselves cannot contain
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whitespace. They may be followed by an optional number,
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the weight of the edge; the number can be negative and can be in
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scientific notation. If there is no weight specified to an edge it
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is assumed to be zero.
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</p>
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<p>
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The resulting graph is always undirected.
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LGL cannot deal with files which contain multiple or loop edges,
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this is however not checked here, as <span class="command"><strong>igraph</strong></span> is happy with
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these.
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</p>
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<p><b>Arguments: </b>
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</p>
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<div class="variablelist"><table border="0" class="variablelist">
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<colgroup>
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<col align="left" valign="top">
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<col>
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||
</colgroup>
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<tbody>
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<tr>
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<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
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<td><p>
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Pointer to an uninitialized graph object.
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</p></td>
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</tr>
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<tr>
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<td><p><span class="term"><em class="parameter"><code>instream</code></em>:</span></p></td>
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<td><p>
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Pointer to a stream, it should be readable.
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</p></td>
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</tr>
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<tr>
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<td><p><span class="term"><em class="parameter"><code>predefnames</code></em>:</span></p></td>
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<td><p>
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Pointer to the symbolic names of the vertices in
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the file. If <code class="constant">NULL</code> is given here then vertex IDs will be
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assigned to vertex names in the order of their appearance in
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the <code class="literal">.ncol</code> file. If it is not <code class="constant">NULL</code> and some unknown
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vertex names are found in the <code class="literal">.ncol</code> file then new vertex
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ids will be assigned to them.
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</p></td>
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</tr>
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<tr>
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<td><p><span class="term"><em class="parameter"><code>names</code></em>:</span></p></td>
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<td><p>
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Boolean value. If <code class="constant">true</code>, the symbolic names of the
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vertices will be added to the graph as a vertex attribute
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called <span class="quote">“<span class="quote">name</span>”</span>.
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</p></td>
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</tr>
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<tr>
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<td><p><span class="term"><em class="parameter"><code>weights</code></em>:</span></p></td>
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<td><p>
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Whether to add the weights of the edges to the
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graph as an edge attribute called <span class="quote">“<span class="quote">weight</span>”</span>.
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<code class="constant">IGRAPH_ADD_WEIGHTS_YES</code> adds the weights (even if they
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are not present in the file, in this case they are assumed
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to be 1). <code class="constant">IGRAPH_ADD_WEIGHTS_NO</code> does not add any
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edge attribute. <code class="constant">IGRAPH_ADD_WEIGHTS_IF_PRESENT</code> adds the
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attribute if and only if there is at least one explicit
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edge weight in the input file, and edges without an explicit
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weight are assumed to have a weight of 1.
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</p></td>
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</tr>
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<tr>
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<td><p><span class="term"><em class="parameter"><code>directed</code></em>:</span></p></td>
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<td><p>
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Whether to create a directed graph. As this format
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was originally used only for undirected graphs there is no
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information in the file about the directedness of the graph.
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Set this parameter to <code class="constant">IGRAPH_DIRECTED</code> or <code class="constant">IGRAPH_UNDIRECTED</code> to create a directed or undirected graph.
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</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code:
|
||
<code class="constant">IGRAPH_PARSEERROR</code>: if there is a
|
||
problem reading
|
||
the file, or the file is syntactically incorrect.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity:
|
||
O(|V|+|E|log(|V|)) if we neglect
|
||
the time required by the parsing. As usual
|
||
|V| is the number of vertices,
|
||
while |E| is the number of edges.
|
||
|
||
</p>
|
||
<p><b>See also: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
<a class="link" href="igraph-Foreign.html#igraph_read_graph_lgl" title="1.5. igraph_read_graph_lgl — Reads a graph from an .lgl file."><code class="function">igraph_read_graph_lgl()</code></a>, <a class="link" href="igraph-Foreign.html#igraph_write_graph_ncol" title="1.4. igraph_write_graph_ncol — Writes the graph to a file in .ncol format."><code class="function">igraph_write_graph_ncol()</code></a>
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_write_graph_ncol"></a>1.4. <code class="function">igraph_write_graph_ncol</code> — Writes the graph to a file in <code class="literal">.ncol</code> format.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.5.5.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_write_graph_ncol(const igraph_t *graph, FILE *outstream,
|
||
const char *names, const char *weights);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
|
||
</p>
|
||
<p>
|
||
<code class="literal">.ncol</code> is a format used by LGL, see <a class="link" href="igraph-Foreign.html#igraph_read_graph_ncol" title="1.3. igraph_read_graph_ncol — Reads an .ncol file used by LGL."><code class="function">igraph_read_graph_ncol()</code></a> for details.
|
||
|
||
</p>
|
||
<p>
|
||
Note that having multiple or loop edges in an
|
||
<code class="literal">.ncol</code> file breaks the LGL software but
|
||
<span class="command"><strong>igraph</strong></span> does not check for this condition.
|
||
|
||
</p>
|
||
<p>
|
||
This format cannot represent zero-degree vertices.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
The graph to write.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>outstream</code></em>:</span></p></td>
|
||
<td><p>
|
||
The stream object to write to, it should be
|
||
writable.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>names</code></em>:</span></p></td>
|
||
<td><p>
|
||
The name of a string vertex attribute, if symbolic names
|
||
are to be written to the file. Supply <code class="constant">NULL</code> to write vertex
|
||
ids instead.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>weights</code></em>:</span></p></td>
|
||
<td><p>
|
||
The name of a numerical edge attribute, which will be
|
||
written as weights to the file. Supply <code class="constant">NULL</code> to skip writing
|
||
edge weights.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code:
|
||
<code class="constant">IGRAPH_EFILE</code> if there is an error writing the
|
||
file.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: O(|E|), the
|
||
number of edges. All file operations are expected to have time
|
||
complexity O(1).
|
||
|
||
</p>
|
||
<p><b>See also: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
<a class="link" href="igraph-Foreign.html#igraph_read_graph_ncol" title="1.3. igraph_read_graph_ncol — Reads an .ncol file used by LGL."><code class="function">igraph_read_graph_ncol()</code></a>, <a class="link" href="igraph-Foreign.html#igraph_write_graph_lgl" title="1.6. igraph_write_graph_lgl — Writes the graph to a file in .lgl format."><code class="function">igraph_write_graph_lgl()</code></a>
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_read_graph_lgl"></a>1.5. <code class="function">igraph_read_graph_lgl</code> — Reads a graph from an <code class="literal">.lgl</code> file.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.5.6.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_read_graph_lgl(igraph_t *graph, FILE *instream,
|
||
igraph_bool_t names,
|
||
igraph_add_weights_t weights,
|
||
igraph_bool_t directed);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
|
||
The <code class="literal">.lgl</code> format is used by the Large Graph
|
||
Layout visualization software
|
||
(<a class="ulink" href="https://lgl.sourceforge.net" target="_top">https://lgl.sourceforge.net</a>), it can
|
||
describe undirected optionally weighted graphs. From the LGL
|
||
manual:
|
||
|
||
</p>
|
||
<div class="blockquote"><blockquote class="blockquote">
|
||
<p>The second format is the LGL file format
|
||
(<code class="literal">.lgl</code> file
|
||
suffix). This is yet another graph file format that tries to be as
|
||
stingy as possible with space, yet keeping the edge file in a human
|
||
readable (not binary) format. The format itself is like the
|
||
following:
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting"> # vertex1name
|
||
vertex2name [optionalWeight]
|
||
vertex3name [optionalWeight] </pre></div>
|
||
<p>
|
||
Here, the first vertex of an edge is preceded with a pound sign
|
||
'#'. Then each vertex that shares an edge with that vertex is
|
||
listed one per line on subsequent lines.</p>
|
||
</blockquote></div>
|
||
<p>
|
||
|
||
</p>
|
||
<p>
|
||
LGL cannot handle loop and multiple edges or directed graphs, but
|
||
in <span class="command"><strong>igraph</strong></span> it is not an error to have multiple and loop edges.
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
Pointer to an uninitialized graph object.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>instream</code></em>:</span></p></td>
|
||
<td><p>
|
||
A stream, it should be readable.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>names</code></em>:</span></p></td>
|
||
<td><p>
|
||
Boolean value, if <code class="constant">true</code> the symbolic names of the
|
||
vertices will be added to the graph as a vertex attribute
|
||
called <span class="quote">“<span class="quote">name</span>”</span>.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>weights</code></em>:</span></p></td>
|
||
<td><p>
|
||
Whether to add the weights of the edges to the
|
||
graph as an edge attribute called <span class="quote">“<span class="quote">weight</span>”</span>.
|
||
<code class="constant">IGRAPH_ADD_WEIGHTS_YES</code> adds the weights (even if they
|
||
are not present in the file, in this case they are assumed
|
||
to be 1). <code class="constant">IGRAPH_ADD_WEIGHTS_NO</code> does not add any
|
||
edge attribute. <code class="constant">IGRAPH_ADD_WEIGHTS_IF_PRESENT</code> adds the
|
||
attribute if and only if there is at least one explicit
|
||
edge weight in the input file, and edges without an explicit
|
||
weight are assumed to have a weight of 1.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>directed</code></em>:</span></p></td>
|
||
<td><p>
|
||
Whether to create a directed graph. As this format
|
||
was originally used only for undirected graphs there is no
|
||
information in the file about the directedness of the graph.
|
||
Set this parameter to <code class="constant">IGRAPH_DIRECTED</code> or <code class="constant">IGRAPH_UNDIRECTED</code> to create a directed or undirected graph.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code:
|
||
<code class="constant">IGRAPH_PARSEERROR</code>: if there is a
|
||
problem reading the file, or the file is syntactically
|
||
incorrect.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity:
|
||
O(|V|+|E|log(|V|)) if we neglect
|
||
the time required by the parsing. As usual
|
||
|V| is the number of vertices,
|
||
while |E| is the number of edges.
|
||
|
||
</p>
|
||
<p><b>See also: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
<a class="link" href="igraph-Foreign.html#igraph_read_graph_ncol" title="1.3. igraph_read_graph_ncol — Reads an .ncol file used by LGL."><code class="function">igraph_read_graph_ncol()</code></a>, <a class="link" href="igraph-Foreign.html#igraph_write_graph_lgl" title="1.6. igraph_write_graph_lgl — Writes the graph to a file in .lgl format."><code class="function">igraph_write_graph_lgl()</code></a>
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
<div class="hideshow" onClick="toggle(this, event)">
|
||
<div class="example">
|
||
<a name="id-1.32.5.6.11.1"></a><p class="title"><b>Example 31.1. File <code class="code">examples/simple/igraph_read_graph_lgl.c</code></b></p>
|
||
<div class="example-contents">
|
||
<pre class="programlisting"><span class="strong"><strong>#include</strong></span> <igraph.h>
|
||
|
||
int <span class="strong"><strong>main</strong></span>(void) {
|
||
igraph_t g;
|
||
FILE *input;
|
||
|
||
<span class="emphasis"><em>/* Initialize the library. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_setup" title="4.1. igraph_setup — Initializes the igraph library.">igraph_setup</a></strong></span>();
|
||
|
||
<span class="emphasis"><em>/* Turn on attribute handling. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Attributes.html#igraph_set_attribute_table" title="1.2. igraph_set_attribute_table — Attach an attribute table.">igraph_set_attribute_table</a></strong></span>(&igraph_cattribute_table);
|
||
|
||
<span class="emphasis"><em>/* Without names and weights */</em></span>
|
||
input = <span class="strong"><strong>fopen</strong></span>("igraph_read_graph_lgl-1.lgl", "r");
|
||
<span class="strong"><strong>if</strong></span> (!input) {
|
||
<span class="strong"><strong>return</strong></span> 1;
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_lgl" title="1.5. igraph_read_graph_lgl — Reads a graph from an .lgl file.">igraph_read_graph_lgl</a></strong></span>(&g, input, 0, IGRAPH_ADD_WEIGHTS_NO, 1);
|
||
<span class="strong"><strong>fclose</strong></span>(input);
|
||
<span class="strong"><strong>if</strong></span> (!<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_is_directed" title="5.2.3. igraph_is_directed — Is this a directed graph?">igraph_is_directed</a></strong></span>(&g)) {
|
||
<span class="strong"><strong>return</strong></span> 2;
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_edgelist" title="1.2. igraph_write_graph_edgelist — Writes the edge list of a graph to a file.">igraph_write_graph_edgelist</a></strong></span>(&g, stdout);
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&g);
|
||
|
||
<span class="emphasis"><em>/* With names and weights */</em></span>
|
||
input = <span class="strong"><strong>fopen</strong></span>("igraph_read_graph_lgl-2.lgl", "r");
|
||
<span class="strong"><strong>if</strong></span> (!input) {
|
||
<span class="strong"><strong>return</strong></span> 3;
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_lgl" title="1.5. igraph_read_graph_lgl — Reads a graph from an .lgl file.">igraph_read_graph_lgl</a></strong></span>(&g, input, 0, IGRAPH_ADD_WEIGHTS_NO, 1);
|
||
<span class="strong"><strong>fclose</strong></span>(input);
|
||
<span class="strong"><strong>if</strong></span> (!<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_is_directed" title="5.2.3. igraph_is_directed — Is this a directed graph?">igraph_is_directed</a></strong></span>(&g)) {
|
||
<span class="strong"><strong>return</strong></span> 4;
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_ncol" title="1.4. igraph_write_graph_ncol — Writes the graph to a file in .ncol format.">igraph_write_graph_ncol</a></strong></span>(&g, stdout, 0, 0);
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&g);
|
||
|
||
<span class="emphasis"><em>/* Same graph, but forcing undirected mode */</em></span>
|
||
input = <span class="strong"><strong>fopen</strong></span>("igraph_read_graph_lgl-2.lgl", "r");
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_lgl" title="1.5. igraph_read_graph_lgl — Reads a graph from an .lgl file.">igraph_read_graph_lgl</a></strong></span>(&g, input, 0, IGRAPH_ADD_WEIGHTS_NO, 0);
|
||
<span class="strong"><strong>fclose</strong></span>(input);
|
||
<span class="strong"><strong>if</strong></span> (<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_is_directed" title="5.2.3. igraph_is_directed — Is this a directed graph?">igraph_is_directed</a></strong></span>(&g)) {
|
||
<span class="strong"><strong>return</strong></span> 5;
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_ncol" title="1.4. igraph_write_graph_ncol — Writes the graph to a file in .ncol format.">igraph_write_graph_ncol</a></strong></span>(&g, stdout, 0, 0);
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&g);
|
||
|
||
<span class="emphasis"><em>/* Erroneous LGL file (empty vertex name) */</em></span>
|
||
input = <span class="strong"><strong>fopen</strong></span>("igraph_read_graph_lgl-3.lgl", "r");
|
||
<span class="strong"><strong>if</strong></span> (!input) {
|
||
<span class="strong"><strong>return</strong></span> 6;
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Error.html#igraph_set_error_handler" title="5.1.1. igraph_set_error_handler — Sets a new error handler.">igraph_set_error_handler</a></strong></span>(<a class="link" href="igraph-Error.html#igraph_error_handler_ignore" title="2.3. igraph_error_handler_ignore — Ignore errors.">igraph_error_handler_ignore</a>);
|
||
<span class="strong"><strong>if</strong></span> (<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_lgl" title="1.5. igraph_read_graph_lgl — Reads a graph from an .lgl file.">igraph_read_graph_lgl</a></strong></span>(&g, input, 0, IGRAPH_ADD_WEIGHTS_NO, 1) !=
|
||
IGRAPH_PARSEERROR) {
|
||
<span class="strong"><strong>return</strong></span> 7;
|
||
}
|
||
<span class="strong"><strong>fclose</strong></span>(input);
|
||
|
||
<span class="strong"><strong>return</strong></span> 0;
|
||
}
|
||
</pre>
|
||
<p></p>
|
||
</div>
|
||
</div>
|
||
<br class="example-break">
|
||
</div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_write_graph_lgl"></a>1.6. <code class="function">igraph_write_graph_lgl</code> — Writes the graph to a file in <code class="literal">.lgl</code> format.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.5.7.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_write_graph_lgl(const igraph_t *graph, FILE *outstream,
|
||
const char *names, const char *weights,
|
||
igraph_bool_t isolates);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
|
||
<code class="literal">.lgl</code> is a format used by LGL, see <a class="link" href="igraph-Foreign.html#igraph_read_graph_lgl" title="1.5. igraph_read_graph_lgl — Reads a graph from an .lgl file."><code class="function">igraph_read_graph_lgl()</code></a> for details.
|
||
|
||
</p>
|
||
<p>
|
||
Note that having multiple or loop edges in an
|
||
<code class="literal">.lgl</code> file breaks the LGL software but <span class="command"><strong>igraph</strong></span>
|
||
does not check for this condition.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
The graph to write.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>outstream</code></em>:</span></p></td>
|
||
<td><p>
|
||
The stream object to write to, it should be
|
||
writable.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>names</code></em>:</span></p></td>
|
||
<td><p>
|
||
The name of a string vertex attribute, if symbolic names
|
||
are to be written to the file. Supply <code class="constant">NULL</code> to write vertex
|
||
ids instead.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>weights</code></em>:</span></p></td>
|
||
<td><p>
|
||
The name of a numerical edge attribute, which will be
|
||
written as weights to the file. Supply <code class="constant">NULL</code> to skip writing
|
||
edge weights.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>isolates</code></em>:</span></p></td>
|
||
<td><p>
|
||
If <code class="constant">true</code>, isolated vertices are also written
|
||
to the file. If <code class="constant">false</code>, they will be omitted.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code:
|
||
<code class="constant">IGRAPH_EFILE</code> if there is an error
|
||
writing the file.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: O(|E|), the number of edges if <em class="parameter"><code>isolates</code></em> is <code class="constant">false</code>,
|
||
O(|V|+|E|) otherwise. All file operations are expected to have
|
||
time complexity O(1).
|
||
|
||
</p>
|
||
<p><b>See also: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
<a class="link" href="igraph-Foreign.html#igraph_read_graph_lgl" title="1.5. igraph_read_graph_lgl — Reads a graph from an .lgl file."><code class="function">igraph_read_graph_lgl()</code></a>, <a class="link" href="igraph-Foreign.html#igraph_write_graph_ncol" title="1.4. igraph_write_graph_ncol — Writes the graph to a file in .ncol format."><code class="function">igraph_write_graph_ncol()</code></a>
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
<div class="hideshow" onClick="toggle(this, event)">
|
||
<div class="example">
|
||
<a name="id-1.32.5.7.11.1"></a><p class="title"><b>Example 31.2. File <code class="code">examples/simple/igraph_write_graph_lgl.c</code></b></p>
|
||
<div class="example-contents">
|
||
<pre class="programlisting"><span class="strong"><strong>#include</strong></span> <igraph.h>
|
||
|
||
int <span class="strong"><strong>main</strong></span>(void) {
|
||
|
||
igraph_t graph;
|
||
igraph_strvector_t names;
|
||
<a class="link" href="igraph-Data-structures.html#igraph_vector_t" title="2.1. About igraph_vector_t objects">igraph_vector_t</a> weights;
|
||
igraph_int_t i;
|
||
igraph_int_t vcount, ecount;
|
||
|
||
<span class="emphasis"><em>/* Initialize the library. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_setup" title="4.1. igraph_setup — Initializes the igraph library.">igraph_setup</a></strong></span>();
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Attributes.html#igraph_set_attribute_table" title="1.2. igraph_set_attribute_table — Attach an attribute table.">igraph_set_attribute_table</a></strong></span>(&igraph_cattribute_table);
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Generators.html#igraph_small" title="2.2. igraph_small — Shorthand to create a small graph, giving the edges as arguments.">igraph_small</a></strong></span>(&graph, 7, IGRAPH_UNDIRECTED,
|
||
0,1, 1,3, 1,2, 2,0, 4,2, 3,4,
|
||
-1);
|
||
vcount = <span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_vcount" title="5.2.1. igraph_vcount — The number of vertices in a graph.">igraph_vcount</a></strong></span>(&graph);
|
||
ecount = <span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_ecount" title="5.2.2. igraph_ecount — The number of edges in a graph.">igraph_ecount</a></strong></span>(&graph);
|
||
|
||
|
||
<span class="strong"><strong>printf</strong></span>("Output without isolates:\n");
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_lgl" title="1.6. igraph_write_graph_lgl — Writes the graph to a file in .lgl format.">igraph_write_graph_lgl</a></strong></span>(&graph, stdout, <span class="emphasis"><em>/*names*/</em></span> NULL, <span class="emphasis"><em>/*weights*/</em></span> NULL, <span class="emphasis"><em>/*isolates*/</em></span> 0);
|
||
|
||
|
||
<span class="strong"><strong>printf</strong></span>("\nOutput with isolates:\n");
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_lgl" title="1.6. igraph_write_graph_lgl — Writes the graph to a file in .lgl format.">igraph_write_graph_lgl</a></strong></span>(&graph, stdout, <span class="emphasis"><em>/*names*/</em></span> NULL, <span class="emphasis"><em>/*weights*/</em></span> NULL, <span class="emphasis"><em>/*isolates*/</em></span> 1);
|
||
|
||
|
||
<span class="strong"><strong>printf</strong></span>("\nOutput vertex and edge labels:\n");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_init" title="8.1. igraph_strvector_init — Initializes a string vector.">igraph_strvector_init</a></strong></span>(&names, vcount);
|
||
<span class="strong"><strong>for</strong></span> (i = 0; i < vcount; i++) {
|
||
char str[2] = " "; <span class="emphasis"><em>/* initialize to ensure presence of null terminator */</em></span>
|
||
str[0] = 'A' + i;
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_set" title="8.6. igraph_strvector_set — Sets an element of the string vector from a string.">igraph_strvector_set</a></strong></span>(&names, i, str);
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Attributes.html#SETVASV" title="4.2.24. SETVASV — Set a string vertex attribute for all vertices">SETVASV</a></strong></span>(&graph, "names", &names);
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_vector_init_range" title="2.2.4. igraph_vector_init_range — Initializes a vector with a range.">igraph_vector_init_range</a></strong></span>(&weights, 1, ecount + 1);
|
||
<span class="strong"><strong><a class="link" href="igraph-Attributes.html#SETEANV" title="4.2.26. SETEANV — Set a numeric edge attribute for all edges">SETEANV</a></strong></span>(&graph, "weights", &weights);
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_lgl" title="1.6. igraph_write_graph_lgl — Writes the graph to a file in .lgl format.">igraph_write_graph_lgl</a></strong></span>(&graph, stdout, "names", "weights", <span class="emphasis"><em>/*isolates*/</em></span> 0);
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_destroy" title="8.3. igraph_strvector_destroy — Frees the memory allocated for the string vector.">igraph_strvector_destroy</a></strong></span>(&names);
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_vector_destroy" title="2.2.5. igraph_vector_destroy — Destroys a vector object.">igraph_vector_destroy</a></strong></span>(&weights);
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&graph);
|
||
|
||
<span class="strong"><strong>return</strong></span> 0;
|
||
}
|
||
</pre>
|
||
<p></p>
|
||
</div>
|
||
</div>
|
||
<br class="example-break">
|
||
</div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_read_graph_dimacs_flow"></a>1.7. <code class="function">igraph_read_graph_dimacs_flow</code> — Read a graph in DIMACS format.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.5.8.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_read_graph_dimacs_flow(
|
||
igraph_t *graph, FILE *instream,
|
||
igraph_strvector_t *problem,
|
||
igraph_vector_int_t *label,
|
||
igraph_int_t *source,
|
||
igraph_int_t *target,
|
||
igraph_vector_t *capacity,
|
||
igraph_bool_t directed);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
This function reads the DIMACS file format, more specifically the
|
||
version for network flow problems, see the files at
|
||
<a class="ulink" href="http://archive.dimacs.rutgers.edu/pub/netflow/general-info/" target="_top">http://archive.dimacs.rutgers.edu/pub/netflow/general-info/</a>
|
||
|
||
</p>
|
||
<p>
|
||
This is a line-oriented text file (ASCII) format. The first
|
||
character of each line defines the type of the line. If the first
|
||
character is <code class="constant">c</code> the line is a comment line and it is
|
||
ignored. There is one problem line (<code class="constant">p</code> in the file), it
|
||
must appear before any node and arc descriptor lines. The problem
|
||
line has three fields separated by spaces: the problem type
|
||
(<code class="constant">max</code> or <code class="constant">edge</code>), the number of vertices,
|
||
and number of edges in the graph. In MAX problems,
|
||
exactly two node identification lines are expected
|
||
(<code class="constant">n</code>), one for the source, and one for the target vertex.
|
||
These have two fields: the ID of the vertex and the type of the
|
||
vertex, either <code class="constant">s</code> ( = source) or <code class="constant">t</code> ( = target).
|
||
Arc lines start with <code class="constant">a</code> and have three fields: the source vertex,
|
||
the target vertex and the edge capacity. In EDGE problems,
|
||
there may be a node line (<code class="constant">n</code>) for each node. It specifies the
|
||
node index and an integer node label. Nodes for which no explicit
|
||
label was specified will use their index as label. In EDGE problems,
|
||
each edge is specified as an edge line (<code class="constant">e</code>).
|
||
|
||
</p>
|
||
<p>
|
||
Within DIMACS files, vertex IDs are numbered from 1.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
Pointer to an uninitialized graph object.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>instream</code></em>:</span></p></td>
|
||
<td><p>
|
||
The file to read from.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>problem</code></em>:</span></p></td>
|
||
<td><p>
|
||
If not <code class="constant">NULL</code>, it will contain the problem type.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>label</code></em>:</span></p></td>
|
||
<td><p>
|
||
If not <code class="constant">NULL</code>, node labels will be stored here for <code class="constant">edge</code>
|
||
problems. Ignored for <code class="constant">max</code> problems.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>source</code></em>:</span></p></td>
|
||
<td><p>
|
||
Pointer to an integer, the ID of the source node will
|
||
be stored here. (The igraph vertex ID, which is one less than
|
||
the actual number in the file.) It is ignored if <code class="constant">NULL</code>.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>target</code></em>:</span></p></td>
|
||
<td><p>
|
||
Pointer to an integer, the (igraph) ID of the target
|
||
node will be stored here. It is ignored if <code class="constant">NULL</code>.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>capacity</code></em>:</span></p></td>
|
||
<td><p>
|
||
Pointer to an initialized vector, the capacity of
|
||
the edges will be stored here if not \ NULL.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>directed</code></em>:</span></p></td>
|
||
<td><p>
|
||
Boolean, whether to create a directed graph.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: O(|V|+|E|+c), the number of vertices plus the
|
||
number of edges, plus the size of the file in characters.
|
||
|
||
</p>
|
||
<p><b>See also: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
<a class="link" href="igraph-Foreign.html#igraph_write_graph_dimacs_flow" title="1.8. igraph_write_graph_dimacs_flow — Write a graph in DIMACS format."><code class="function">igraph_write_graph_dimacs_flow()</code></a>
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_write_graph_dimacs_flow"></a>1.8. <code class="function">igraph_write_graph_dimacs_flow</code> — Write a graph in DIMACS format.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.5.9.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_write_graph_dimacs_flow(const igraph_t *graph, FILE *outstream,
|
||
igraph_int_t source, igraph_int_t target,
|
||
const igraph_vector_t *capacity);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
This function writes a graph to an output stream in DIMACS format,
|
||
describing a maximum flow problem.
|
||
See ftp://dimacs.rutgers.edu/pub/netflow/general-info/
|
||
|
||
</p>
|
||
<p>
|
||
This file format is discussed in the documentation of <a class="link" href="igraph-Foreign.html#igraph_read_graph_dimacs_flow" title="1.7. igraph_read_graph_dimacs_flow — Read a graph in DIMACS format."><code class="function">igraph_read_graph_dimacs_flow()</code></a>, see that for more information.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
The graph to write to the stream.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>outstream</code></em>:</span></p></td>
|
||
<td><p>
|
||
The stream.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>source</code></em>:</span></p></td>
|
||
<td><p>
|
||
Integer, the id of the source vertex for the maximum
|
||
flow.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>target</code></em>:</span></p></td>
|
||
<td><p>
|
||
Integer, the id of the target vertex.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>capacity</code></em>:</span></p></td>
|
||
<td><p>
|
||
Pointer to an initialized vector containing the
|
||
edge capacity values.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: O(|E|), the number of edges in the graph.
|
||
|
||
</p>
|
||
<p><b>See also: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
<a class="link" href="igraph-Foreign.html#igraph_read_graph_dimacs_flow" title="1.7. igraph_read_graph_dimacs_flow — Read a graph in DIMACS format."><code class="function">igraph_read_graph_dimacs_flow()</code></a>
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
</div>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||
<a name="binary-formats"></a>2. Binary formats</h2></div></div></div>
|
||
<div class="toc"><dl class="toc"><dt><span class="section"><a href="igraph-Foreign.html#igraph_read_graph_graphdb">2.1. <code class="function">igraph_read_graph_graphdb</code> — Read a graph in the binary graph database format.</a></span></dt></dl></div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_read_graph_graphdb"></a>2.1. <code class="function">igraph_read_graph_graphdb</code> — Read a graph in the binary graph database format.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.6.2.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_read_graph_graphdb(igraph_t *graph, FILE *instream,
|
||
igraph_bool_t directed);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
This is a binary format, used in the ARG Graph Database
|
||
for isomorphism testing. For more information, see
|
||
<a class="ulink" href="https://mivia.unisa.it/datasets/graph-database/arg-database/" target="_top">https://mivia.unisa.it/datasets/graph-database/arg-database/</a>
|
||
|
||
</p>
|
||
<p>
|
||
From the graph database homepage:
|
||
</p>
|
||
<div class="blockquote"><blockquote class="blockquote">
|
||
<p>
|
||
The graphs are stored in a compact binary format, one graph per
|
||
file. The file is composed of 16 bit words, which are represented
|
||
using the so-called little-endian convention, i.e. the least
|
||
significant byte of the word is stored first.</p>
|
||
<p>
|
||
Then, for each node, the file contains the list of edges coming
|
||
out of the node itself. The list is represented by a word encoding
|
||
its length, followed by a word for each edge, representing the
|
||
destination node of the edge. Node numeration is 0-based, so the
|
||
first node of the graph has index 0.</p>
|
||
</blockquote></div>
|
||
<p>
|
||
As of igraph 0.10, only unlabelled graphs are implemented.
|
||
</p>
|
||
<p>
|
||
References:
|
||
</p>
|
||
<p>
|
||
M. De Santo, P. Foggia, C. Sansone, and M. Vento:
|
||
A large database of graphs and its use for benchmarking graph isomorphism algorithms.
|
||
Pattern Recognition Letters, 24(8), 1067-1079 (2003).
|
||
<a class="ulink" href="https://doi.org/10.1016/S0167-8655(02)00253-2" target="_top">https://doi.org/10.1016/S0167-8655(02)00253-2</a>
|
||
</p>
|
||
<p>
|
||
MIVIA ARG Dataset,
|
||
<a class="ulink" href="https://zenodo.org/records/11204020" target="_top">https://zenodo.org/records/11204020</a>,
|
||
<a class="ulink" href="https://mivia.unisa.it/datasets/graph-database/arg-database/" target="_top">https://mivia.unisa.it/datasets/graph-database/arg-database/</a>
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
Pointer to an uninitialized graph object.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>instream</code></em>:</span></p></td>
|
||
<td><p>
|
||
The stream to read from. It should be opened
|
||
in binary mode.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>directed</code></em>:</span></p></td>
|
||
<td><p>
|
||
Whether to create a directed graph.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: O(|V|+|E|), the number of vertices plus the
|
||
number of edges.
|
||
|
||
</p>
|
||
<div class="hideshow" onClick="toggle(this, event)">
|
||
<div class="example">
|
||
<a name="id-1.32.6.2.14.1"></a><p class="title"><b>Example 31.3. File <code class="code">examples/simple/igraph_read_graph_graphdb.c</code></b></p>
|
||
<div class="example-contents">
|
||
<pre class="programlisting"><span class="strong"><strong>#include</strong></span> <igraph.h>
|
||
|
||
int <span class="strong"><strong>main</strong></span>(void) {
|
||
igraph_t g;
|
||
FILE *input;
|
||
|
||
<span class="emphasis"><em>/* Initialize the library. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_setup" title="4.1. igraph_setup — Initializes the igraph library.">igraph_setup</a></strong></span>();
|
||
|
||
input = <span class="strong"><strong>fopen</strong></span>("iso_b03_m1000.A00", "rb");
|
||
<span class="strong"><strong>if</strong></span> (!input) {
|
||
<span class="strong"><strong>return</strong></span> 1;
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_graphdb" title="2.1. igraph_read_graph_graphdb — Read a graph in the binary graph database format.">igraph_read_graph_graphdb</a></strong></span>(&g, input, IGRAPH_DIRECTED);
|
||
<span class="strong"><strong>fclose</strong></span>(input);
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_edgelist" title="1.2. igraph_write_graph_edgelist — Writes the edge list of a graph to a file.">igraph_write_graph_edgelist</a></strong></span>(&g, stdout);
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&g);
|
||
|
||
<span class="strong"><strong>return</strong></span> 0;
|
||
}
|
||
</pre>
|
||
<p></p>
|
||
</div>
|
||
</div>
|
||
<br class="example-break">
|
||
</div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||
<a name="graphml-format"></a>3. GraphML format</h2></div></div></div>
|
||
<div class="toc"><dl class="toc">
|
||
<dt><span class="section"><a href="igraph-Foreign.html#igraph_read_graph_graphml">3.1. <code class="function">igraph_read_graph_graphml</code> — Reads a graph from a GraphML file.</a></span></dt>
|
||
<dt><span class="section"><a href="igraph-Foreign.html#igraph_write_graph_graphml">3.2. <code class="function">igraph_write_graph_graphml</code> — Writes the graph to a file in GraphML format.</a></span></dt>
|
||
</dl></div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_read_graph_graphml"></a>3.1. <code class="function">igraph_read_graph_graphml</code> — Reads a graph from a GraphML file.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.7.2.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_read_graph_graphml(igraph_t *graph, FILE *instream, igraph_int_t index);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
|
||
</p>
|
||
<p>
|
||
GraphML is an XML-based file format for representing various types of
|
||
graphs. Currently only the most basic import functionality is implemented
|
||
in igraph: it can read GraphML files without nested graphs and hyperedges.
|
||
Attributes of the graph are loaded only if an attribute interface
|
||
is attached, see <a class="link" href="igraph-Attributes.html#igraph_set_attribute_table" title="1.2. igraph_set_attribute_table — Attach an attribute table."><code class="function">igraph_set_attribute_table()</code></a>. String attrribute values
|
||
are returned in UTF-8 encoding.
|
||
|
||
</p>
|
||
<p>
|
||
Graph attribute names are taken from the <code class="literal">attr.name</code> attributes of the
|
||
<code class="constant">key</code> tags in the GraphML file. Since <code class="literal">attr.name</code> is not mandatory,
|
||
igraph will fall back to the <code class="constant">id</code> attribute of the <code class="constant">key</code> tag if
|
||
<code class="literal">attr.name</code> is missing.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
Pointer to an uninitialized graph object.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>instream</code></em>:</span></p></td>
|
||
<td><p>
|
||
A stream, it should be readable.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>index</code></em>:</span></p></td>
|
||
<td><p>
|
||
If the GraphML file contains more than one graph, the one
|
||
specified by this index will be loaded. Indices start from
|
||
zero, so supply zero here if your GraphML file contains only
|
||
a single graph.</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code:
|
||
<code class="constant">IGRAPH_PARSEERROR</code>: if there is a
|
||
problem reading the file, or the file is syntactically
|
||
incorrect.
|
||
<code class="constant">IGRAPH_UNIMPLEMENTED</code>: the GraphML functionality was disabled
|
||
at compile-time
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
<div class="hideshow" onClick="toggle(this, event)">
|
||
<div class="example">
|
||
<a name="id-1.32.7.2.10.1"></a><p class="title"><b>Example 31.4. File <code class="code">examples/simple/graphml.c</code></b></p>
|
||
<div class="example-contents">
|
||
<pre class="programlisting"><span class="strong"><strong>#include</strong></span> <igraph.h>
|
||
<span class="strong"><strong>#include</strong></span> <stdio.h>
|
||
<span class="strong"><strong>#include</strong></span> <unistd.h> <span class="emphasis"><em>/* unlink */</em></span>
|
||
|
||
int <span class="strong"><strong>main</strong></span>(void) {
|
||
igraph_t graph;
|
||
<span class="strong"><strong>const</strong></span> char *infilename = "test.graphml";
|
||
<span class="strong"><strong>const</strong></span> char *outfilename = "test2.graphml";
|
||
|
||
<span class="emphasis"><em>/* Initialize the library. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_setup" title="4.1. igraph_setup — Initializes the igraph library.">igraph_setup</a></strong></span>();
|
||
|
||
<span class="emphasis"><em>/* Set up attribute handling, so graph attributes can be imported</em></span>
|
||
<span class="emphasis"><em> * from the GraphML file. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Attributes.html#igraph_set_attribute_table" title="1.2. igraph_set_attribute_table — Attach an attribute table.">igraph_set_attribute_table</a></strong></span>(&igraph_cattribute_table);
|
||
|
||
<span class="emphasis"><em>/* Problems in the GraphML file may cause igraph to print warnings.</em></span>
|
||
<span class="emphasis"><em> * If this is not desired, set a silent warning handler: */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Error.html#igraph_set_warning_handler" title="4.2. igraph_set_warning_handler — Installs a warning handler.">igraph_set_warning_handler</a></strong></span>(&<a class="link" href="igraph-Error.html#igraph_warning_handler_ignore" title="4.7. igraph_warning_handler_ignore — Ignores all warnings.">igraph_warning_handler_ignore</a>);
|
||
|
||
<span class="emphasis"><em>/* Read the contents of a GraphML file. */</em></span>
|
||
|
||
<span class="emphasis"><em>/* GraphML */</em></span>
|
||
FILE *infile = <span class="strong"><strong>fopen</strong></span>("test.graphml", "r");
|
||
<span class="strong"><strong>if</strong></span> (! infile) {
|
||
<span class="strong"><strong>fprintf</strong></span>(stderr, "Could not open input file '%s'.", infilename);
|
||
<span class="strong"><strong>exit</strong></span>(1);
|
||
}
|
||
|
||
<span class="emphasis"><em>/* GraphML support is an optional feature in igraph. If igraph was compiled</em></span>
|
||
<span class="emphasis"><em> * without GraphML support, igraph_read_graph_graphml() returns IGRAPH_UNIMPLEMENTED.</em></span>
|
||
<span class="emphasis"><em> * We temporarily disable the default error handler so we can test for this condition. */</em></span>
|
||
<a class="link" href="igraph-Error.html#igraph_error_handler_t" title="2.1. igraph_error_handler_t — The type of error handler functions.">igraph_error_handler_t</a> *oldhandler = <span class="strong"><strong><a class="link" href="igraph-Error.html#igraph_set_error_handler" title="5.1.1. igraph_set_error_handler — Sets a new error handler.">igraph_set_error_handler</a></strong></span>(<a class="link" href="igraph-Error.html#igraph_error_handler_ignore" title="2.3. igraph_error_handler_ignore — Ignore errors.">igraph_error_handler_ignore</a>);
|
||
<a class="link" href="igraph-Error.html#igraph_error_t" title="3.1. igraph_error_t — Return type for functions returning an error code.">igraph_error_t</a> ret = <span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_graphml" title="3.1. igraph_read_graph_graphml — Reads a graph from a GraphML file.">igraph_read_graph_graphml</a></strong></span>(&graph, infile, 0);
|
||
<span class="strong"><strong>if</strong></span> (ret == IGRAPH_UNIMPLEMENTED) {
|
||
<span class="strong"><strong>fprintf</strong></span>(stderr, "igraph was compiled without GraphML support.");
|
||
<span class="strong"><strong>exit</strong></span>(77);
|
||
}
|
||
<span class="strong"><strong>if</strong></span> (ret != IGRAPH_SUCCESS) {
|
||
<span class="strong"><strong>fprintf</strong></span>(stderr, "Unexpected error while reading GraphML.");
|
||
<span class="strong"><strong>exit</strong></span>(1);
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Error.html#igraph_set_error_handler" title="5.1.1. igraph_set_error_handler — Sets a new error handler.">igraph_set_error_handler</a></strong></span>(oldhandler);
|
||
|
||
|
||
<span class="strong"><strong>fclose</strong></span>(infile);
|
||
|
||
<span class="emphasis"><em>/* Write it back into another file. */</em></span>
|
||
|
||
FILE *outfile = <span class="strong"><strong>fopen</strong></span>(outfilename, "w");
|
||
<span class="strong"><strong>if</strong></span> (outfile) {
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_graphml" title="3.2. igraph_write_graph_graphml — Writes the graph to a file in GraphML format.">igraph_write_graph_graphml</a></strong></span>(&graph, outfile, true);
|
||
<span class="strong"><strong>fclose</strong></span>(outfile);
|
||
|
||
<span class="emphasis"><em>/* Clean up after ourselves */</em></span>
|
||
<span class="strong"><strong>unlink</strong></span>(outfilename);
|
||
} <span class="strong"><strong>else</strong></span> {
|
||
<span class="strong"><strong>fprintf</strong></span>(stderr, "Could not write output file '%s'.", outfilename);
|
||
}
|
||
|
||
<span class="emphasis"><em>/* Destroy the graph */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&graph);
|
||
|
||
<span class="strong"><strong>return</strong></span> 0;
|
||
}
|
||
</pre>
|
||
<p></p>
|
||
</div>
|
||
</div>
|
||
<br class="example-break">
|
||
</div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_write_graph_graphml"></a>3.2. <code class="function">igraph_write_graph_graphml</code> — Writes the graph to a file in GraphML format.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.7.3.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_write_graph_graphml(const igraph_t *graph, FILE *outstream,
|
||
igraph_bool_t prefixattr);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
|
||
GraphML is an XML-based file format for representing various types of
|
||
graphs. See the GraphML Primer (<a class="ulink" href="http://graphml.graphdrawing.org/primer/graphml-primer.html" target="_top">http://graphml.graphdrawing.org/primer/graphml-primer.html</a>)
|
||
for the detailed format description.
|
||
|
||
</p>
|
||
<p>
|
||
When a numerical attribute value is NaN, it will be omitted from the file.
|
||
|
||
</p>
|
||
<p>
|
||
This function assumes that non-ASCII characters in attribute names and string
|
||
attribute values are UTF-8 encoded. If this is not the case, the resulting
|
||
XML file will be invalid. Control characters, i.e. character codes up to and
|
||
including 31 (with the exception of tab, cr and lf), are not allowed.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
The graph to write.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>outstream</code></em>:</span></p></td>
|
||
<td><p>
|
||
The stream object to write to, it should be
|
||
writable.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>prefixattr</code></em>:</span></p></td>
|
||
<td><p>
|
||
Boolean value. Whether to put a prefix in front of the
|
||
attribute names to ensure uniqueness if the graph has vertex and
|
||
edge (or graph) attributes with the same name.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code:
|
||
<code class="constant">IGRAPH_EFILE</code> if there is an error
|
||
writing the file.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: O(|V|+|E|) otherwise. All
|
||
file operations are expected to have time complexity
|
||
O(1).
|
||
|
||
</p>
|
||
<div class="hideshow" onClick="toggle(this, event)">
|
||
<div class="example">
|
||
<a name="id-1.32.7.3.10.1"></a><p class="title"><b>Example 31.5. File <code class="code">examples/simple/graphml.c</code></b></p>
|
||
<div class="example-contents">
|
||
<pre class="programlisting"><span class="strong"><strong>#include</strong></span> <igraph.h>
|
||
<span class="strong"><strong>#include</strong></span> <stdio.h>
|
||
<span class="strong"><strong>#include</strong></span> <unistd.h> <span class="emphasis"><em>/* unlink */</em></span>
|
||
|
||
int <span class="strong"><strong>main</strong></span>(void) {
|
||
igraph_t graph;
|
||
<span class="strong"><strong>const</strong></span> char *infilename = "test.graphml";
|
||
<span class="strong"><strong>const</strong></span> char *outfilename = "test2.graphml";
|
||
|
||
<span class="emphasis"><em>/* Initialize the library. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_setup" title="4.1. igraph_setup — Initializes the igraph library.">igraph_setup</a></strong></span>();
|
||
|
||
<span class="emphasis"><em>/* Set up attribute handling, so graph attributes can be imported</em></span>
|
||
<span class="emphasis"><em> * from the GraphML file. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Attributes.html#igraph_set_attribute_table" title="1.2. igraph_set_attribute_table — Attach an attribute table.">igraph_set_attribute_table</a></strong></span>(&igraph_cattribute_table);
|
||
|
||
<span class="emphasis"><em>/* Problems in the GraphML file may cause igraph to print warnings.</em></span>
|
||
<span class="emphasis"><em> * If this is not desired, set a silent warning handler: */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Error.html#igraph_set_warning_handler" title="4.2. igraph_set_warning_handler — Installs a warning handler.">igraph_set_warning_handler</a></strong></span>(&<a class="link" href="igraph-Error.html#igraph_warning_handler_ignore" title="4.7. igraph_warning_handler_ignore — Ignores all warnings.">igraph_warning_handler_ignore</a>);
|
||
|
||
<span class="emphasis"><em>/* Read the contents of a GraphML file. */</em></span>
|
||
|
||
<span class="emphasis"><em>/* GraphML */</em></span>
|
||
FILE *infile = <span class="strong"><strong>fopen</strong></span>("test.graphml", "r");
|
||
<span class="strong"><strong>if</strong></span> (! infile) {
|
||
<span class="strong"><strong>fprintf</strong></span>(stderr, "Could not open input file '%s'.", infilename);
|
||
<span class="strong"><strong>exit</strong></span>(1);
|
||
}
|
||
|
||
<span class="emphasis"><em>/* GraphML support is an optional feature in igraph. If igraph was compiled</em></span>
|
||
<span class="emphasis"><em> * without GraphML support, igraph_read_graph_graphml() returns IGRAPH_UNIMPLEMENTED.</em></span>
|
||
<span class="emphasis"><em> * We temporarily disable the default error handler so we can test for this condition. */</em></span>
|
||
<a class="link" href="igraph-Error.html#igraph_error_handler_t" title="2.1. igraph_error_handler_t — The type of error handler functions.">igraph_error_handler_t</a> *oldhandler = <span class="strong"><strong><a class="link" href="igraph-Error.html#igraph_set_error_handler" title="5.1.1. igraph_set_error_handler — Sets a new error handler.">igraph_set_error_handler</a></strong></span>(<a class="link" href="igraph-Error.html#igraph_error_handler_ignore" title="2.3. igraph_error_handler_ignore — Ignore errors.">igraph_error_handler_ignore</a>);
|
||
<a class="link" href="igraph-Error.html#igraph_error_t" title="3.1. igraph_error_t — Return type for functions returning an error code.">igraph_error_t</a> ret = <span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_graphml" title="3.1. igraph_read_graph_graphml — Reads a graph from a GraphML file.">igraph_read_graph_graphml</a></strong></span>(&graph, infile, 0);
|
||
<span class="strong"><strong>if</strong></span> (ret == IGRAPH_UNIMPLEMENTED) {
|
||
<span class="strong"><strong>fprintf</strong></span>(stderr, "igraph was compiled without GraphML support.");
|
||
<span class="strong"><strong>exit</strong></span>(77);
|
||
}
|
||
<span class="strong"><strong>if</strong></span> (ret != IGRAPH_SUCCESS) {
|
||
<span class="strong"><strong>fprintf</strong></span>(stderr, "Unexpected error while reading GraphML.");
|
||
<span class="strong"><strong>exit</strong></span>(1);
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Error.html#igraph_set_error_handler" title="5.1.1. igraph_set_error_handler — Sets a new error handler.">igraph_set_error_handler</a></strong></span>(oldhandler);
|
||
|
||
|
||
<span class="strong"><strong>fclose</strong></span>(infile);
|
||
|
||
<span class="emphasis"><em>/* Write it back into another file. */</em></span>
|
||
|
||
FILE *outfile = <span class="strong"><strong>fopen</strong></span>(outfilename, "w");
|
||
<span class="strong"><strong>if</strong></span> (outfile) {
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_graphml" title="3.2. igraph_write_graph_graphml — Writes the graph to a file in GraphML format.">igraph_write_graph_graphml</a></strong></span>(&graph, outfile, true);
|
||
<span class="strong"><strong>fclose</strong></span>(outfile);
|
||
|
||
<span class="emphasis"><em>/* Clean up after ourselves */</em></span>
|
||
<span class="strong"><strong>unlink</strong></span>(outfilename);
|
||
} <span class="strong"><strong>else</strong></span> {
|
||
<span class="strong"><strong>fprintf</strong></span>(stderr, "Could not write output file '%s'.", outfilename);
|
||
}
|
||
|
||
<span class="emphasis"><em>/* Destroy the graph */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&graph);
|
||
|
||
<span class="strong"><strong>return</strong></span> 0;
|
||
}
|
||
</pre>
|
||
<p></p>
|
||
</div>
|
||
</div>
|
||
<br class="example-break">
|
||
</div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||
<a name="gml-format"></a>4. GML format</h2></div></div></div>
|
||
<div class="toc"><dl class="toc">
|
||
<dt><span class="section"><a href="igraph-Foreign.html#igraph_read_graph_gml">4.1. <code class="function">igraph_read_graph_gml</code> — Read a graph in GML format.</a></span></dt>
|
||
<dt><span class="section"><a href="igraph-Foreign.html#igraph_write_graph_gml">4.2. <code class="function">igraph_write_graph_gml</code> — Write the graph to a stream in GML format.</a></span></dt>
|
||
</dl></div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_read_graph_gml"></a>4.1. <code class="function">igraph_read_graph_gml</code> — Read a graph in GML format.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.8.2.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_read_graph_gml(igraph_t *graph, FILE *instream);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
GML is a simple textual format, see
|
||
<a class="ulink" href="https://web.archive.org/web/20190207140002/http://www.fim.uni-passau.de/index.php?id=17297%26L=1" target="_top">https://web.archive.org/web/20190207140002/http://www.fim.uni-passau.de/index.php?id=17297%26L=1</a>
|
||
for details.
|
||
|
||
</p>
|
||
<p>
|
||
Although all syntactically correct GML can be parsed,
|
||
we implement only a subset of this format. Some attributes might be
|
||
ignored. Here is a list of all the differences:
|
||
</p>
|
||
<div class="orderedlist"><ol class="orderedlist" type="1">
|
||
<li class="listitem"><p>
|
||
Only attributes with a simple type are used: integer, real or
|
||
string. If an attribute is composite, i.e. an array or a record,
|
||
then it is ignored. When some values of the attribute are simple and
|
||
some compound, the composite ones are replaced with a default value
|
||
(NaN for numeric, <code class="literal">""</code> for string).
|
||
|
||
</p></li>
|
||
<li class="listitem"><p>
|
||
<code class="literal">comment</code> fields are not ignored. They are treated as any
|
||
other field and converted to attributes.
|
||
|
||
</p></li>
|
||
<li class="listitem"><p>
|
||
Top level attributes except for <code class="literal">Version</code> and the
|
||
first <code class="literal">graph</code> attribute are completely ignored.
|
||
|
||
</p></li>
|
||
<li class="listitem"><p>
|
||
There is no maximum line length or maximum keyword length.
|
||
|
||
</p></li>
|
||
<li class="listitem"><p>
|
||
Only the <code class="constant">quot</code>, <code class="constant">amp</code>, <code class="constant">apos</code>, <code class="constant">lt</code> and <code class="constant">gt</code> character entities
|
||
are supported. Any other entity is passed through unchanged by the reader
|
||
after issuing a warning, and is expected to be decoded by the user.
|
||
|
||
</p></li>
|
||
<li class="listitem"><p>
|
||
We allow <code class="literal">inf</code>, <code class="literal">-inf</code> and <code class="literal">nan</code>
|
||
(not a number) as a real number. This is case insensitive, so
|
||
<code class="literal">nan</code>, <code class="literal">NaN</code> and <code class="literal">NAN</code> are equivalent.
|
||
|
||
</p></li>
|
||
</ol></div>
|
||
<p>
|
||
|
||
</p>
|
||
<p> Please contact us if you cannot live with these
|
||
limitations of the GML parser.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
Pointer to an uninitialized graph object.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>instream</code></em>:</span></p></td>
|
||
<td><p>
|
||
The stream to read the GML file from.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: should be proportional to the length of the file.
|
||
|
||
</p>
|
||
<p><b>See also: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
<a class="link" href="igraph-Foreign.html#igraph_read_graph_graphml" title="3.1. igraph_read_graph_graphml — Reads a graph from a GraphML file."><code class="function">igraph_read_graph_graphml()</code></a> for a more modern format,
|
||
<a class="link" href="igraph-Foreign.html#igraph_write_graph_gml" title="4.2. igraph_write_graph_gml — Write the graph to a stream in GML format."><code class="function">igraph_write_graph_gml()</code></a> for writing GML files.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
<div class="hideshow" onClick="toggle(this, event)">
|
||
<div class="example">
|
||
<a name="id-1.32.8.2.12.1"></a><p class="title"><b>Example 31.6. File <code class="code">examples/simple/gml.c</code></b></p>
|
||
<div class="example-contents">
|
||
<pre class="programlisting"><span class="strong"><strong>#include</strong></span> <igraph.h>
|
||
<span class="strong"><strong>#include</strong></span> <stdio.h>
|
||
|
||
int <span class="strong"><strong>main</strong></span>(void) {
|
||
igraph_t graph;
|
||
FILE *ifile;
|
||
|
||
<span class="emphasis"><em>/* Initialize the library. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_setup" title="4.1. igraph_setup — Initializes the igraph library.">igraph_setup</a></strong></span>();
|
||
|
||
ifile = <span class="strong"><strong>fopen</strong></span>("karate.gml", "r");
|
||
<span class="strong"><strong>if</strong></span> (ifile == 0) {
|
||
<span class="strong"><strong>return</strong></span> 1;
|
||
}
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_gml" title="4.1. igraph_read_graph_gml — Read a graph in GML format.">igraph_read_graph_gml</a></strong></span>(&graph, ifile);
|
||
<span class="strong"><strong>fclose</strong></span>(ifile);
|
||
|
||
<span class="strong"><strong>printf</strong></span>("The graph is %s.\n", <span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_is_directed" title="5.2.3. igraph_is_directed — Is this a directed graph?">igraph_is_directed</a></strong></span>(&graph) ? "directed" : "undirected");
|
||
|
||
<span class="emphasis"><em>/* Output as edge list */</em></span>
|
||
<span class="strong"><strong>printf</strong></span>("\n-----------------\n");
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_edgelist" title="1.2. igraph_write_graph_edgelist — Writes the edge list of a graph to a file.">igraph_write_graph_edgelist</a></strong></span>(&graph, stdout);
|
||
|
||
<span class="emphasis"><em>/* Output as GML */</em></span>
|
||
<span class="strong"><strong>printf</strong></span>("\n-----------------\n");
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_gml" title="4.2. igraph_write_graph_gml — Write the graph to a stream in GML format.">igraph_write_graph_gml</a></strong></span>(&graph, stdout,IGRAPH_WRITE_GML_DEFAULT_SW, 0, "");
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&graph);
|
||
|
||
<span class="strong"><strong>return</strong></span> 0;
|
||
}
|
||
</pre>
|
||
<p></p>
|
||
</div>
|
||
</div>
|
||
<br class="example-break">
|
||
</div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_write_graph_gml"></a>4.2. <code class="function">igraph_write_graph_gml</code> — Write the graph to a stream in GML format.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.8.3.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_write_graph_gml(const igraph_t *graph, FILE *outstream,
|
||
igraph_write_gml_sw_t options,
|
||
const igraph_vector_t *id, const char *creator);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
GML is a quite general textual format, see
|
||
<a class="ulink" href="https://web.archive.org/web/20190207140002/http://www.fim.uni-passau.de/index.php?id=17297%26L=1" target="_top">https://web.archive.org/web/20190207140002/http://www.fim.uni-passau.de/index.php?id=17297%26L=1</a>
|
||
for details.
|
||
|
||
</p>
|
||
<p>
|
||
The graph, vertex and edges attributes are written to the
|
||
file as well, if they are numeric or string. Boolean attributes are converted
|
||
to numeric, with 0 and 1 used for false and true, respectively.
|
||
NaN values of numeric attributes are skipped, as NaN is not part of the GML
|
||
specification and other software may not be able to read files containing them.
|
||
This is consistent with <a class="link" href="igraph-Foreign.html#igraph_read_graph_gml" title="4.1. igraph_read_graph_gml — Read a graph in GML format."><code class="function">igraph_read_graph_gml()</code></a>, which produces NaN
|
||
when an attribute value is missing. In contrast with NaN, infinite values
|
||
are retained. Ensure that none of the numeric attributes values are infinite
|
||
to produce a conformant GML file that can be read by other software.
|
||
|
||
</p>
|
||
<p>
|
||
As igraph is more forgiving about attribute names, it might
|
||
be necessary to simplify the them before writing to the GML file.
|
||
This way we'll have a syntactically correct GML file. The following
|
||
simple procedure is performed on each attribute name: first the alphanumeric
|
||
characters are extracted, the others are ignored. Then if the first character
|
||
is not a letter then the attribute name is prefixed with <span class="quote">“<span class="quote">igraph</span>”</span>.
|
||
Note that this might result identical names for two attributes, igraph
|
||
does not check this.
|
||
|
||
</p>
|
||
<p>
|
||
The <span class="quote">“<span class="quote">id</span>”</span> vertex attribute is treated specially.
|
||
If the <em class="parameter"><code>id</code></em> argument is not <code class="constant">NULL</code> then it should be a numeric
|
||
vector with the vertex IDs and the <span class="quote">“<span class="quote">id</span>”</span> vertex attribute is
|
||
ignored (if there is one). If <em class="parameter"><code>id</code></em> is <code class="constant">NULL</code> and there is a
|
||
numeric <span class="quote">“<span class="quote">id</span>”</span> vertex attribute, it will be used instead. If ids
|
||
are not specified in either way then the regular igraph vertex IDs are used.
|
||
If some of the supplied id values are invalid (non-integer or NaN), all supplied
|
||
id are ignored and igraph vertex IDs are used instead.
|
||
|
||
</p>
|
||
<p>
|
||
Note that whichever way vertex IDs are specified, their uniqueness is not checked.
|
||
|
||
</p>
|
||
<p>
|
||
If the graph has edge attributes that become <span class="quote">“<span class="quote">source</span>”</span>
|
||
or <span class="quote">“<span class="quote">target</span>”</span> after encoding, or the graph has an attribute that becomes
|
||
<span class="quote">“<span class="quote">directed</span>”</span>, they will be ignored with a warning. GML uses these attributes
|
||
to specify the edge endpoints, and the graph directedness, so we cannot write them
|
||
to the file. Rename them before calling this function if you want to preserve them.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
The graph to write to the stream.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>outstream</code></em>:</span></p></td>
|
||
<td><p>
|
||
The stream to write the file to.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>options</code></em>:</span></p></td>
|
||
<td>
|
||
<p>
|
||
Set of <code class="literal">|</code>-combinable boolean flags for writing the GML file.
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><code class="constant">0</code></span></p></td>
|
||
<td><p>
|
||
|
||
All options turned off.
|
||
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><code class="constant">IGRAPH_WRITE_GML_DEFAULT_SW</code></span></p></td>
|
||
<td><p>
|
||
|
||
Default options, currently equivalent to 0. May change in future versions.
|
||
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><code class="constant">IGRAPH_WRITE_GML_ENCODE_ONLY_QUOT_SW</code></span></p></td>
|
||
<td><p>
|
||
|
||
Do not encode any other characters than " as entities. Specifically, this
|
||
option prevents the encoding of &. Useful when re-exporting a graph
|
||
that was read from a GML file in which igraph could not interpret all entities,
|
||
and thus passed them through without decoding.
|
||
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>id</code></em>:</span></p></td>
|
||
<td><p>
|
||
Either <code class="literal">NULL</code> or a numeric vector with the vertex IDs.
|
||
See details above.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>creator</code></em>:</span></p></td>
|
||
<td><p>
|
||
An optional string to write to the stream in the creator line.
|
||
If <code class="constant">NULL</code>, the igraph version with the current date and time is added.
|
||
If <code class="literal">""</code>, the creator line is omitted. Otherwise, the
|
||
supplied string is used verbatim.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: should be proportional to the number of characters written
|
||
to the file.
|
||
|
||
</p>
|
||
<p><b>See also: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
<a class="link" href="igraph-Foreign.html#igraph_read_graph_gml" title="4.1. igraph_read_graph_gml — Read a graph in GML format."><code class="function">igraph_read_graph_gml()</code></a> for reading GML files,
|
||
<a class="link" href="igraph-Foreign.html#igraph_read_graph_graphml" title="3.1. igraph_read_graph_graphml — Reads a graph from a GraphML file."><code class="function">igraph_read_graph_graphml()</code></a> for a more modern format.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
<div class="hideshow" onClick="toggle(this, event)">
|
||
<div class="example">
|
||
<a name="id-1.32.8.3.15.1"></a><p class="title"><b>Example 31.7. File <code class="code">examples/simple/gml.c</code></b></p>
|
||
<div class="example-contents">
|
||
<pre class="programlisting"><span class="strong"><strong>#include</strong></span> <igraph.h>
|
||
<span class="strong"><strong>#include</strong></span> <stdio.h>
|
||
|
||
int <span class="strong"><strong>main</strong></span>(void) {
|
||
igraph_t graph;
|
||
FILE *ifile;
|
||
|
||
<span class="emphasis"><em>/* Initialize the library. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_setup" title="4.1. igraph_setup — Initializes the igraph library.">igraph_setup</a></strong></span>();
|
||
|
||
ifile = <span class="strong"><strong>fopen</strong></span>("karate.gml", "r");
|
||
<span class="strong"><strong>if</strong></span> (ifile == 0) {
|
||
<span class="strong"><strong>return</strong></span> 1;
|
||
}
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_gml" title="4.1. igraph_read_graph_gml — Read a graph in GML format.">igraph_read_graph_gml</a></strong></span>(&graph, ifile);
|
||
<span class="strong"><strong>fclose</strong></span>(ifile);
|
||
|
||
<span class="strong"><strong>printf</strong></span>("The graph is %s.\n", <span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_is_directed" title="5.2.3. igraph_is_directed — Is this a directed graph?">igraph_is_directed</a></strong></span>(&graph) ? "directed" : "undirected");
|
||
|
||
<span class="emphasis"><em>/* Output as edge list */</em></span>
|
||
<span class="strong"><strong>printf</strong></span>("\n-----------------\n");
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_edgelist" title="1.2. igraph_write_graph_edgelist — Writes the edge list of a graph to a file.">igraph_write_graph_edgelist</a></strong></span>(&graph, stdout);
|
||
|
||
<span class="emphasis"><em>/* Output as GML */</em></span>
|
||
<span class="strong"><strong>printf</strong></span>("\n-----------------\n");
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_gml" title="4.2. igraph_write_graph_gml — Write the graph to a stream in GML format.">igraph_write_graph_gml</a></strong></span>(&graph, stdout,IGRAPH_WRITE_GML_DEFAULT_SW, 0, "");
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&graph);
|
||
|
||
<span class="strong"><strong>return</strong></span> 0;
|
||
}
|
||
</pre>
|
||
<p></p>
|
||
</div>
|
||
</div>
|
||
<br class="example-break">
|
||
</div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||
<a name="pajek-format"></a>5. Pajek format</h2></div></div></div>
|
||
<div class="toc"><dl class="toc">
|
||
<dt><span class="section"><a href="igraph-Foreign.html#igraph_read_graph_pajek">5.1. <code class="function">igraph_read_graph_pajek</code> — Reads a file in Pajek format.</a></span></dt>
|
||
<dt><span class="section"><a href="igraph-Foreign.html#igraph_write_graph_pajek">5.2. <code class="function">igraph_write_graph_pajek</code> — Writes a graph to a file in Pajek format.</a></span></dt>
|
||
</dl></div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_read_graph_pajek"></a>5.1. <code class="function">igraph_read_graph_pajek</code> — Reads a file in Pajek format.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.9.2.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_read_graph_pajek(igraph_t *graph, FILE *instream);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
Only a subset of the Pajek format is implemented. This is partially
|
||
because there is no formal specification for this format, but also because
|
||
<span class="command"><strong>igraph</strong></span> does not support some Pajek features, like
|
||
mixed graphs.
|
||
|
||
</p>
|
||
<p>
|
||
Starting from version 0.6.1 igraph reads bipartite (two-mode)
|
||
graphs from Pajek files and adds the <code class="constant">type</code> Boolean vertex attribute for
|
||
them. Warnings are given for invalid edges, i.e. edges connecting
|
||
vertices of the same type.
|
||
|
||
</p>
|
||
<p>
|
||
The list of the current limitations:
|
||
</p>
|
||
<div class="orderedlist"><ol class="orderedlist" type="1">
|
||
<li class="listitem"><p>
|
||
Only <code class="filename">.net</code> files are supported, Pajek
|
||
project files (<code class="filename">.paj</code>) are not.
|
||
|
||
</p></li>
|
||
<li class="listitem"><p>
|
||
Temporal networks (i.e. with time events) are not supported.
|
||
|
||
</p></li>
|
||
<li class="listitem"><p>
|
||
Graphs with both directed and non-directed edges are not
|
||
supported, as they cannot be represented in <span class="command"><strong>igraph</strong></span>.
|
||
|
||
</p></li>
|
||
<li class="listitem"><p>
|
||
Only Pajek networks are supported; permutations, hierarchies,
|
||
clusters and vectors are not.
|
||
|
||
</p></li>
|
||
<li class="listitem"><p>
|
||
Multi-relational networks (i.e. networks with multiple edge
|
||
types) are not supported.
|
||
|
||
</p></li>
|
||
<li class="listitem"><p>
|
||
Unicode characters encoded as <code class="literal">&#dddd;</code>, or newlines
|
||
encoded as <code class="literal">\n</code> will not be decoded.
|
||
|
||
</p></li>
|
||
</ol></div>
|
||
<p>
|
||
|
||
</p>
|
||
<p>
|
||
If an attribute handler is installed,
|
||
<span class="command"><strong>igraph</strong></span> also reads the vertex and edge attributes
|
||
from the file. Most attributes are renamed to be more informative:
|
||
<code class="constant">color</code> instead of <code class="constant">c</code>, <code class="constant">xfact</code> instead of <code class="constant">x_fact</code>,
|
||
<code class="constant">yfact</code> instead of y_fact, <code class="constant">labeldist</code> instead of <code class="constant">lr</code>,
|
||
<code class="constant">labeldegree2</code> instead of <code class="constant">lphi</code>, <code class="constant">framewidth</code> instead of <code class="constant">bw</code>,
|
||
<code class="constant">fontsize</code> instead of <code class="constant">fos</code>, <code class="constant">rotation</code> instead of <code class="constant">phi</code>,
|
||
<code class="constant">radius</code> instead of <code class="constant">r</code>, <code class="constant">diamondratio</code> instead of <code class="constant">q</code>,
|
||
<code class="constant">labeldegree</code> instead of <code class="constant">la</code>,
|
||
<code class="constant">color</code> instead of <code class="constant">ic</code>, <code class="constant">framecolor</code> instead of <code class="constant">bc</code>,
|
||
<code class="constant">labelcolor</code> instead of <code class="constant">lc</code>; these belong to vertices.
|
||
|
||
</p>
|
||
<p>
|
||
Edge attributes are also renamed, <code class="constant">s</code> to <code class="constant">arrowsize</code>,
|
||
<code class="constant">w</code> to <code class="constant">edgewidth</code>, <code class="constant">h1</code> to <code class="constant">hook1</code>, <code class="constant">h2</code> to <code class="constant">hook2</code>,
|
||
<code class="constant">a1</code> to <code class="constant">angle1</code>, <code class="constant">a2</code> to <code class="constant">angle2</code>, <code class="constant">k1</code> to
|
||
<code class="constant">velocity1</code>, <code class="constant">k2</code> to <code class="constant">velocity2</code>, <code class="constant">ap</code> to <code class="constant">arrowpos</code>,
|
||
<code class="constant">lp</code> to <code class="constant">labelpos</code>, <code class="constant">lr</code> to <code class="constant">labelangle</code>,
|
||
<code class="constant">lphi</code> to <code class="constant">labelangle2</code>, <code class="constant">la</code> to <code class="constant">labeldegree</code>,
|
||
<code class="constant">fos</code> to <code class="constant">fontsize</code>, <code class="constant">a</code> to <code class="constant">arrowtype</code>, <code class="constant">p</code> to <code class="constant">linepattern</code>,
|
||
<code class="constant">l</code> to <code class="constant">label</code>, <code class="constant">lc</code> to <code class="constant">labelcolor</code>, <code class="constant">c</code> to <code class="constant">color</code>.
|
||
|
||
</p>
|
||
<p>
|
||
Unknown vertex or edge parameters are read as string vertex
|
||
or edge attributes. If the parameter name conflicts with one
|
||
the standard attribute names mentioned above, a <code class="literal">_</code>
|
||
character is appended to it to avoid conflict.
|
||
|
||
</p>
|
||
<p>
|
||
In addition the following vertex attributes might be added: <code class="constant">name</code> is added
|
||
(with the same value) if there are vertex IDs in the file.
|
||
<code class="constant">x</code> and <code class="constant">y</code>, and potentially <code class="constant">z</code> are also added if there are vertex
|
||
coordinates in the file.
|
||
|
||
</p>
|
||
<p>
|
||
The <code class="constant">weight</code> edge attribute will be added if there are edge weights present.
|
||
|
||
</p>
|
||
<p>
|
||
See the Pajek homepage:
|
||
<a class="ulink" href="http://vlado.fmf.uni-lj.si/pub/networks/pajek/" target="_top">http://vlado.fmf.uni-lj.si/pub/networks/pajek/</a> for more info on
|
||
Pajek. The Pajek manual,
|
||
<a class="ulink" href="http://vlado.fmf.uni-lj.si/pub/networks/pajek/doc/pajekman.pdf" target="_top">http://vlado.fmf.uni-lj.si/pub/networks/pajek/doc/pajekman.pdf</a>,
|
||
and <a class="ulink" href="http://mrvar.fdv.uni-lj.si/pajek/DrawEPS.htm" target="_top">http://mrvar.fdv.uni-lj.si/pajek/DrawEPS.htm</a>
|
||
have information on the Pajek file format. There is additional
|
||
useful information and sample files at
|
||
<a class="ulink" href="http://mrvar.fdv.uni-lj.si/pajek/history.htm" target="_top">http://mrvar.fdv.uni-lj.si/pajek/history.htm</a>
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
Pointer to an uninitialized graph object.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>instream</code></em>:</span></p></td>
|
||
<td><p>
|
||
An already opened file handler.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: O(|V|+|E|+|A|), |V| is the number of vertices, |E|
|
||
the number of edges, |A| the number of attributes (vertex + edge)
|
||
in the graph if there are attribute handlers installed.
|
||
|
||
</p>
|
||
<p><b>See also: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
<a class="link" href="igraph-Foreign.html#igraph_write_graph_pajek" title="5.2. igraph_write_graph_pajek — Writes a graph to a file in Pajek format."><code class="function">igraph_write_graph_pajek()</code></a> for writing Pajek files, <a class="link" href="igraph-Foreign.html#igraph_read_graph_graphml" title="3.1. igraph_read_graph_graphml — Reads a graph from a GraphML file."><code class="function">igraph_read_graph_graphml()</code></a> for reading GraphML files.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
<div class="hideshow" onClick="toggle(this, event)">
|
||
<div class="example">
|
||
<a name="id-1.32.9.2.18.1"></a><p class="title"><b>Example 31.8. File <code class="code">examples/simple/foreign.c</code></b></p>
|
||
<div class="example-contents">
|
||
<pre class="programlisting"><span class="strong"><strong>#include</strong></span> <igraph.h>
|
||
<span class="strong"><strong>#include</strong></span> <stdio.h>
|
||
|
||
int <span class="strong"><strong>main</strong></span>(void) {
|
||
igraph_t g;
|
||
FILE *ifile;
|
||
|
||
<span class="emphasis"><em>/* Initialize the library. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_setup" title="4.1. igraph_setup — Initializes the igraph library.">igraph_setup</a></strong></span>();
|
||
|
||
<span class="emphasis"><em>/* Turn on attribute handling. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Attributes.html#igraph_set_attribute_table" title="1.2. igraph_set_attribute_table — Attach an attribute table.">igraph_set_attribute_table</a></strong></span>(&igraph_cattribute_table);
|
||
|
||
<span class="emphasis"><em>/* Read a Pajek file. */</em></span>
|
||
ifile = <span class="strong"><strong>fopen</strong></span>("links.net", "r");
|
||
<span class="strong"><strong>if</strong></span> (ifile == 0) {
|
||
<span class="strong"><strong>return</strong></span> 10;
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_pajek" title="5.1. igraph_read_graph_pajek — Reads a file in Pajek format.">igraph_read_graph_pajek</a></strong></span>(&g, ifile);
|
||
<span class="strong"><strong>fclose</strong></span>(ifile);
|
||
|
||
<span class="emphasis"><em>/* Write it in edgelist format. */</em></span>
|
||
<span class="strong"><strong>printf</strong></span>("The graph:\n");
|
||
<span class="strong"><strong>printf</strong></span>("Vertices: %" IGRAPH_PRId "\n", <span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_vcount" title="5.2.1. igraph_vcount — The number of vertices in a graph.">igraph_vcount</a></strong></span>(&g));
|
||
<span class="strong"><strong>printf</strong></span>("Edges: %" IGRAPH_PRId "\n", <span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_ecount" title="5.2.2. igraph_ecount — The number of edges in a graph.">igraph_ecount</a></strong></span>(&g));
|
||
<span class="strong"><strong>printf</strong></span>("Directed: %i\n", <span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_is_directed" title="5.2.3. igraph_is_directed — Is this a directed graph?">igraph_is_directed</a></strong></span>(&g) ? 1 : 0);
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_edgelist" title="1.2. igraph_write_graph_edgelist — Writes the edge list of a graph to a file.">igraph_write_graph_edgelist</a></strong></span>(&g, stdout);
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&g);
|
||
|
||
<span class="strong"><strong>return</strong></span> 0;
|
||
}
|
||
</pre>
|
||
<p></p>
|
||
</div>
|
||
</div>
|
||
<br class="example-break">
|
||
</div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_write_graph_pajek"></a>5.2. <code class="function">igraph_write_graph_pajek</code> — Writes a graph to a file in Pajek format.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.9.3.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_write_graph_pajek(const igraph_t *graph, FILE *outstream);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
Writes files in the native format of the Pajek software. This format
|
||
is not recommended for data exchange or archival. It is meant solely
|
||
for interoperability with Pajek.
|
||
|
||
</p>
|
||
<p>
|
||
The Pajek vertex and edge parameters (like color) are determined by
|
||
the attributes of the vertices and edges. Of course this requires
|
||
an attribute handler to be installed. The names of the
|
||
corresponding vertex and edge attributes are listed at <a class="link" href="igraph-Foreign.html#igraph_read_graph_pajek" title="5.1. igraph_read_graph_pajek — Reads a file in Pajek format."><code class="function">igraph_read_graph_pajek()</code></a>, e.g. the <code class="constant">color</code> vertex attributes
|
||
determines the color (<code class="constant">c</code> in Pajek) parameter.
|
||
|
||
</p>
|
||
<p>
|
||
Vertex and edge attributes that do not correspond to any documented
|
||
Pajek parameter are discarded.
|
||
|
||
</p>
|
||
<p>
|
||
As of version 0.6.1 igraph writes bipartite graphs into Pajek files
|
||
correctly, i.e. they will be also bipartite when read into Pajek.
|
||
As Pajek is less flexible for bipartite graphs (the numeric IDs of
|
||
the vertices must be sorted according to vertex type), igraph might
|
||
need to reorder the vertices when writing a bipartite Pajek file.
|
||
This effectively means that numeric vertex IDs usually change when
|
||
a bipartite graph is written to a Pajek file, and then read back
|
||
into igraph.
|
||
|
||
</p>
|
||
<p>
|
||
Early versions of Pajek supported only Windows-style line endings
|
||
in Pajek files, but recent versions support both Windows and Unix
|
||
line endings. igraph therefore uses the platform-native line endings
|
||
when the input file is opened in text mode, and uses Unix-style
|
||
line endings when the input file is opened in binary mode. If you
|
||
are using an old version of Pajek, you are on Unix and you are having
|
||
problems reading files written by igraph on a Windows machine, convert the
|
||
line endings manually with a text editor or with <code class="constant">unix2dos</code> or <code class="constant">iconv</code>
|
||
from the command line).
|
||
|
||
</p>
|
||
<p>
|
||
Pajek will only interpret UTF-8 encoded files if they contain a byte-order
|
||
mark (BOM) at the beginning. igraph is agnostic of string attribute encodings
|
||
and therefore it will never write a BOM. You need to add this manually
|
||
if/when necessary.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
The graph object to write.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>outstream</code></em>:</span></p></td>
|
||
<td><p>
|
||
The file to write to. It should be opened and writable.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: O(|V|+|E|+|A|), |V| is the number of vertices, |E|
|
||
is the number of edges, |A| the number of attributes (vertex +
|
||
edge) in the graph if there are attribute handlers installed.
|
||
|
||
</p>
|
||
<p><b>See also: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
<a class="link" href="igraph-Foreign.html#igraph_read_graph_pajek" title="5.1. igraph_read_graph_pajek — Reads a file in Pajek format."><code class="function">igraph_read_graph_pajek()</code></a> for reading Pajek graphs, <a class="link" href="igraph-Foreign.html#igraph_write_graph_graphml" title="3.2. igraph_write_graph_graphml — Writes the graph to a file in GraphML format."><code class="function">igraph_write_graph_graphml()</code></a> for writing a graph in GraphML format,
|
||
this suites <span class="command"><strong>igraph</strong></span> graphs better.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
<div class="hideshow" onClick="toggle(this, event)">
|
||
<div class="example">
|
||
<a name="id-1.32.9.3.15.1"></a><p class="title"><b>Example 31.9. File <code class="code">examples/simple/igraph_write_graph_pajek.c</code></b></p>
|
||
<div class="example-contents">
|
||
<pre class="programlisting"><span class="strong"><strong>#include</strong></span> <igraph.h>
|
||
|
||
int <span class="strong"><strong>main</strong></span>(void) {
|
||
igraph_t g;
|
||
igraph_strvector_t names;
|
||
|
||
<span class="emphasis"><em>/* Initialize the library. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_setup" title="4.1. igraph_setup — Initializes the igraph library.">igraph_setup</a></strong></span>();
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Attributes.html#igraph_set_attribute_table" title="1.2. igraph_set_attribute_table — Attach an attribute table.">igraph_set_attribute_table</a></strong></span>(&igraph_cattribute_table);
|
||
|
||
<span class="emphasis"><em>/* save a simple ring graph */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Generators.html#igraph_ring" title="4.7. igraph_ring — Creates a cycle graph or a path graph.">igraph_ring</a></strong></span>(&g, 10, IGRAPH_DIRECTED, false <span class="emphasis"><em>/* mutual */</em></span>, true <span class="emphasis"><em>/* circular */</em></span>);
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_pajek" title="5.2. igraph_write_graph_pajek — Writes a graph to a file in Pajek format.">igraph_write_graph_pajek</a></strong></span>(&g, stdout);
|
||
|
||
<span class="emphasis"><em>/* add some vertex attributes */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_init" title="8.1. igraph_strvector_init — Initializes a string vector.">igraph_strvector_init</a></strong></span>(&names, 0);
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "A");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "B");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "C");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "D");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "E");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "F");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "G");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "H");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "I");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "J");
|
||
<span class="strong"><strong><a class="link" href="igraph-Attributes.html#SETVASV" title="4.2.24. SETVASV — Set a string vertex attribute for all vertices">SETVASV</a></strong></span>(&g, "name", &names);
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_destroy" title="8.3. igraph_strvector_destroy — Frees the memory allocated for the string vector.">igraph_strvector_destroy</a></strong></span>(&names);
|
||
|
||
<span class="emphasis"><em>/* save the graph with vertex names */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_pajek" title="5.2. igraph_write_graph_pajek — Writes a graph to a file in Pajek format.">igraph_write_graph_pajek</a></strong></span>(&g, stdout);
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_init" title="8.1. igraph_strvector_init — Initializes a string vector.">igraph_strvector_init</a></strong></span>(&names, 0);
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "square");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "square");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "square");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "square");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "escaping spaces");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "square");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "square");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "escaping\nnewline");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "square");
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_push_back" title="8.8. igraph_strvector_push_back — Adds an element to the back of a string vector.">igraph_strvector_push_back</a></strong></span>(&names, "encoding \"quotes\"");
|
||
<span class="strong"><strong><a class="link" href="igraph-Attributes.html#SETVASV" title="4.2.24. SETVASV — Set a string vertex attribute for all vertices">SETVASV</a></strong></span>(&g, "shape", &names);
|
||
<span class="strong"><strong><a class="link" href="igraph-Data-structures.html#igraph_strvector_destroy" title="8.3. igraph_strvector_destroy — Frees the memory allocated for the string vector.">igraph_strvector_destroy</a></strong></span>(&names);
|
||
|
||
<span class="emphasis"><em>/* save the graph with escaped shapes */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_pajek" title="5.2. igraph_write_graph_pajek — Writes a graph to a file in Pajek format.">igraph_write_graph_pajek</a></strong></span>(&g, stdout);
|
||
|
||
<span class="emphasis"><em>/* destroy the graph */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&g);
|
||
<span class="strong"><strong>return</strong></span> 0;
|
||
}
|
||
</pre>
|
||
<p></p>
|
||
</div>
|
||
</div>
|
||
<br class="example-break">
|
||
</div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||
<a name="ucinets-dl-file-format"></a>6. UCINET's DL file format</h2></div></div></div>
|
||
<div class="toc"><dl class="toc"><dt><span class="section"><a href="igraph-Foreign.html#igraph_read_graph_dl">6.1. <code class="function">igraph_read_graph_dl</code> — Reads a file in the DL format of UCINET.</a></span></dt></dl></div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_read_graph_dl"></a>6.1. <code class="function">igraph_read_graph_dl</code> — Reads a file in the DL format of UCINET.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.10.2.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_read_graph_dl(igraph_t *graph, FILE *instream,
|
||
igraph_bool_t directed);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
This is a simple textual file format used by UCINET. See
|
||
<a class="ulink" href="http://www.analytictech.com/networks/dataentry.htm" target="_top">http://www.analytictech.com/networks/dataentry.htm</a> for
|
||
examples. All the forms described here are supported by
|
||
igraph. Vertex names and edge weights are also supported and they
|
||
are added as attributes. (If an attribute handler is attached.)
|
||
|
||
</p>
|
||
<p> Note the specification does not mention whether the
|
||
format is case sensitive or not. For igraph DL files are case
|
||
sensitive, i.e. <code class="constant">Larry</code> and <code class="constant">larry</code> are not the same.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
Pointer to an uninitialized graph object.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>instream</code></em>:</span></p></td>
|
||
<td><p>
|
||
The stream to read the DL file from.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>directed</code></em>:</span></p></td>
|
||
<td><p>
|
||
Boolean, whether to create a directed file.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: linear in terms of the number of edges and
|
||
vertices, except for the matrix format, which is quadratic in the
|
||
number of vertices.
|
||
|
||
</p>
|
||
<div class="hideshow" onClick="toggle(this, event)">
|
||
<div class="example">
|
||
<a name="id-1.32.10.2.9.1"></a><p class="title"><b>Example 31.10. File <code class="code">examples/simple/igraph_read_graph_dl.c</code></b></p>
|
||
<div class="example-contents">
|
||
<pre class="programlisting"><span class="strong"><strong>#include</strong></span> <igraph.h>
|
||
<span class="strong"><strong>#include</strong></span> <stdio.h>
|
||
<span class="strong"><strong>#include</strong></span> <stdlib.h>
|
||
|
||
int <span class="strong"><strong>main</strong></span>(void) {
|
||
|
||
<span class="strong"><strong>const</strong></span> char *files[] = { "fullmatrix1.dl", "fullmatrix2.dl",
|
||
"fullmatrix3.dl", "fullmatrix4.dl",
|
||
"edgelist1.dl", "edgelist2.dl", "edgelist3.dl",
|
||
"edgelist4.dl", "edgelist5.dl", "edgelist6.dl",
|
||
"edgelist7.dl", "nodelist1.dl", "nodelist2.dl" };
|
||
igraph_t graph;
|
||
FILE *infile;
|
||
|
||
<span class="emphasis"><em>/* Initialize the library. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_setup" title="4.1. igraph_setup — Initializes the igraph library.">igraph_setup</a></strong></span>();
|
||
|
||
<span class="emphasis"><em>/* Turn on attribute handling. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Attributes.html#igraph_set_attribute_table" title="1.2. igraph_set_attribute_table — Attach an attribute table.">igraph_set_attribute_table</a></strong></span>(&igraph_cattribute_table);
|
||
|
||
<span class="strong"><strong>for</strong></span> (size_t i = 0; i < <span class="strong"><strong>sizeof</strong></span>(files) / <span class="strong"><strong>sizeof</strong></span>(files[0]); i++) {
|
||
<span class="strong"><strong>printf</strong></span>("Doing %s\n", files[i]);
|
||
infile = <span class="strong"><strong>fopen</strong></span>(files[i], "r");
|
||
<span class="strong"><strong>if</strong></span> (!infile) {
|
||
<span class="strong"><strong>printf</strong></span>("Cannot open file: %s\n", files[i]);
|
||
<span class="strong"><strong>abort</strong></span>();
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_dl" title="6.1. igraph_read_graph_dl — Reads a file in the DL format of UCINET.">igraph_read_graph_dl</a></strong></span>(&graph, infile, IGRAPH_DIRECTED);
|
||
<span class="strong"><strong>fclose</strong></span>(infile);
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_edgelist" title="1.2. igraph_write_graph_edgelist — Writes the edge list of a graph to a file.">igraph_write_graph_edgelist</a></strong></span>(&graph, stdout);
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&graph);
|
||
}
|
||
|
||
<span class="strong"><strong>if</strong></span> (<span class="strong"><strong>IGRAPH_FINALLY_STACK_SIZE</strong></span>() != 0) {
|
||
<span class="strong"><strong>return</strong></span> 1;
|
||
}
|
||
|
||
<span class="strong"><strong>return</strong></span> 0;
|
||
}
|
||
</pre>
|
||
<p></p>
|
||
</div>
|
||
</div>
|
||
<br class="example-break">
|
||
</div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||
<a name="graphviz-format"></a>7. Graphviz format</h2></div></div></div>
|
||
<div class="toc"><dl class="toc"><dt><span class="section"><a href="igraph-Foreign.html#igraph_write_graph_dot">7.1. <code class="function">igraph_write_graph_dot</code> — Write the graph to a stream in DOT format.</a></span></dt></dl></div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_write_graph_dot"></a>7.1. <code class="function">igraph_write_graph_dot</code> — Write the graph to a stream in DOT format.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.11.2.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_write_graph_dot(const igraph_t *graph, FILE* outstream);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
</p>
|
||
<p>
|
||
DOT is the format used by the widely known GraphViz software, see
|
||
<a class="ulink" href="http://www.graphviz.org" target="_top">http://www.graphviz.org</a> for details. The grammar of the DOT format
|
||
can be found here: <a class="ulink" href="http://www.graphviz.org/doc/info/lang.html" target="_top">http://www.graphviz.org/doc/info/lang.html</a>
|
||
|
||
</p>
|
||
<p>
|
||
This is only a preliminary implementation, no visualization
|
||
information is written.
|
||
|
||
</p>
|
||
<p>
|
||
This format is meant solely for interoperability with Graphviz.
|
||
It is not recommended for data exchange or archival.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
The graph to write to the stream.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>outstream</code></em>:</span></p></td>
|
||
<td><p>
|
||
The stream to write the file to.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: should be proportional to the number of characters written
|
||
to the file.
|
||
|
||
</p>
|
||
<p><b>See also: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
<a class="link" href="igraph-Foreign.html#igraph_write_graph_graphml" title="3.2. igraph_write_graph_graphml — Writes the graph to a file in GraphML format."><code class="function">igraph_write_graph_graphml()</code></a> for a more modern format.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
<div class="hideshow" onClick="toggle(this, event)">
|
||
<div class="example">
|
||
<a name="id-1.32.11.2.13.1"></a><p class="title"><b>Example 31.11. File <code class="code">examples/simple/dot.c</code></b></p>
|
||
<div class="example-contents">
|
||
<pre class="programlisting"><span class="strong"><strong>#include</strong></span> <igraph.h>
|
||
<span class="strong"><strong>#include</strong></span> <stdio.h>
|
||
|
||
int <span class="strong"><strong>main</strong></span>(void) {
|
||
igraph_t g;
|
||
FILE *ifile;
|
||
|
||
<span class="emphasis"><em>/* Initialize the library. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_setup" title="4.1. igraph_setup — Initializes the igraph library.">igraph_setup</a></strong></span>();
|
||
|
||
ifile = <span class="strong"><strong>fopen</strong></span>("karate.gml", "r");
|
||
<span class="strong"><strong>if</strong></span> (ifile == 0) {
|
||
<span class="strong"><strong>return</strong></span> 10;
|
||
}
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_gml" title="4.1. igraph_read_graph_gml — Read a graph in GML format.">igraph_read_graph_gml</a></strong></span>(&g, ifile);
|
||
<span class="strong"><strong>fclose</strong></span>(ifile);
|
||
|
||
<span class="strong"><strong>if</strong></span> (<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_is_directed" title="5.2.3. igraph_is_directed — Is this a directed graph?">igraph_is_directed</a></strong></span>(&g)) {
|
||
<span class="strong"><strong>printf</strong></span>("directed\n");
|
||
} <span class="strong"><strong>else</strong></span> {
|
||
<span class="strong"><strong>printf</strong></span>("undirected\n");
|
||
}
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_edgelist" title="1.2. igraph_write_graph_edgelist — Writes the edge list of a graph to a file.">igraph_write_graph_edgelist</a></strong></span>(&g, stdout);
|
||
<span class="strong"><strong>printf</strong></span>("-----------------\n");
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_dot" title="7.1. igraph_write_graph_dot — Write the graph to a stream in DOT format.">igraph_write_graph_dot</a></strong></span>(&g, stdout);
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&g);
|
||
|
||
<span class="strong"><strong>return</strong></span> 0;
|
||
}
|
||
</pre>
|
||
<p></p>
|
||
</div>
|
||
</div>
|
||
<br class="example-break">
|
||
</div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||
<a name="leda-format"></a>8. LEDA format</h2></div></div></div>
|
||
<div class="toc"><dl class="toc"><dt><span class="section"><a href="igraph-Foreign.html#igraph_write_graph_leda">8.1. <code class="function">igraph_write_graph_leda</code> — Write a graph in LEDA native graph format.</a></span></dt></dl></div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_write_graph_leda"></a>8.1. <code class="function">igraph_write_graph_leda</code> — Write a graph in LEDA native graph format.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.12.2.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_write_graph_leda(const igraph_t *graph, FILE *outstream,
|
||
const char *vertex_attr_name,
|
||
const char *edge_attr_name);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
This function writes a graph to an output stream in LEDA format.
|
||
See <a class="ulink" href="http://www.algorithmic-solutions.info/leda_guide/graphs/leda_native_graph_fileformat.html" target="_top">http://www.algorithmic-solutions.info/leda_guide/graphs/leda_native_graph_fileformat.html</a>
|
||
|
||
</p>
|
||
<p>
|
||
The support for the LEDA format is very basic at the moment; igraph
|
||
writes only the LEDA graph section which supports one selected vertex
|
||
and edge attribute and no layout information or visual attributes.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>graph</code></em>:</span></p></td>
|
||
<td><p>
|
||
The graph to write to the stream.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>outstream</code></em>:</span></p></td>
|
||
<td><p>
|
||
The stream.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>vertex_attr_name</code></em>:</span></p></td>
|
||
<td><p>
|
||
The name of the vertex attribute whose values
|
||
are to be stored in the output, or <code class="constant">NULL</code> if no
|
||
vertex attribute should be stored.
|
||
</p></td>
|
||
</tr>
|
||
<tr>
|
||
<td><p><span class="term"><em class="parameter"><code>edge_attr_name</code></em>:</span></p></td>
|
||
<td><p>
|
||
The name of the edge attribute whose values
|
||
are to be stored in the output, or <code class="constant">NULL</code> if no
|
||
edge attribute should be stored.
|
||
</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
Time complexity: O(|V|+|E|), the number of vertices and edges in the
|
||
graph.
|
||
|
||
</p>
|
||
</div>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||
<a name="locale-helpers"></a>9. Convenience functions for locale change</h2></div></div></div>
|
||
<div class="toc"><dl class="toc">
|
||
<dt><span class="section"><a href="igraph-Foreign.html#igraph_enter_safelocale">9.1. <code class="function">igraph_enter_safelocale</code> — Temporarily set the C locale.</a></span></dt>
|
||
<dt><span class="section"><a href="igraph-Foreign.html#igraph_exit_safelocale">9.2. <code class="function">igraph_exit_safelocale</code> — Temporarily set the C locale.</a></span></dt>
|
||
</dl></div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_enter_safelocale"></a>9.1. <code class="function">igraph_enter_safelocale</code> — Temporarily set the C locale.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.13.2.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
igraph_error_t igraph_enter_safelocale(igraph_safelocale_t *loc);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
igraph's foreign format readers and writers require a locale that uses a
|
||
decimal point instead of a decimal comma. This is a convenience function
|
||
that temporarily sets the C locale so that readers and writers would work
|
||
correctly. It <span class="emphasis"><em>must</em></span> be paired with a call to <a class="link" href="igraph-Foreign.html#igraph_exit_safelocale" title="9.2. igraph_exit_safelocale — Temporarily set the C locale."><code class="function">igraph_exit_safelocale()</code></a>,
|
||
otherwise a memory leak will occur.
|
||
|
||
</p>
|
||
<p>
|
||
This function tries to set the locale for the current thread only on a
|
||
best-effort basis. Restricting the locale change to a single thread is not
|
||
supported on all platforms. In these cases, this function falls back to using
|
||
the standard <code class="literal">setlocale()</code> function, which affects the entire process
|
||
and is not safe to use from concurrent threads.
|
||
|
||
</p>
|
||
<p>
|
||
It is generally recommended to run igraph within a thread that has been
|
||
permanently set to the C locale using system-specific means. This is a convenience
|
||
function for situations when this is not easily possible because the programmer
|
||
is not in control of the process, such as when developing plugins/extensions.
|
||
Note that processes start up in the C locale by default, thus nothing needs to
|
||
be done unless the locale has been changed away from the default.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code>loc</code></em>:</span></p></td>
|
||
<td><p>
|
||
Pointer to a variable of type <code class="constant">igraph_safelocale_t</code>. The current
|
||
locale will be stored here, so that it can be restored using
|
||
<a class="link" href="igraph-Foreign.html#igraph_exit_safelocale" title="9.2. igraph_exit_safelocale — Temporarily set the C locale."><code class="function">igraph_exit_safelocale()</code></a>.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
</p>
|
||
<p><b>Returns: </b></p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code></code></em></span></p></td>
|
||
<td><p>
|
||
Error code.
|
||
</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
</p>
|
||
<div class="hideshow" onClick="toggle(this, event)">
|
||
<div class="example">
|
||
<a name="id-1.32.13.2.10.1"></a><p class="title"><b>Example 31.12. File <code class="code">examples/simple/safelocale.c</code></b></p>
|
||
<div class="example-contents">
|
||
<pre class="programlisting"><span class="strong"><strong>#include</strong></span> <igraph.h>
|
||
|
||
<span class="strong"><strong>#include</strong></span> <locale.h>
|
||
<span class="strong"><strong>#include</strong></span> <stdio.h>
|
||
<span class="strong"><strong>#include</strong></span> <string.h>
|
||
|
||
int <span class="strong"><strong>main</strong></span>(void) {
|
||
<span class="strong"><strong>const</strong></span> char *filename = "weighted.gml";
|
||
igraph_t graph;
|
||
igraph_safelocale_t loc;
|
||
|
||
<span class="emphasis"><em>/* Initialize the library. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_setup" title="4.1. igraph_setup — Initializes the igraph library.">igraph_setup</a></strong></span>();
|
||
|
||
<span class="emphasis"><em>/* Attempt to set a locale that uses a decimal comma. Locale names</em></span>
|
||
<span class="emphasis"><em> * differ between platforms, and not all locales are available,</em></span>
|
||
<span class="emphasis"><em> * so the locale change may not be successful. */</em></span>
|
||
<span class="strong"><strong>const</strong></span> char *locname = <span class="strong"><strong>setlocale</strong></span>(LC_ALL, "de_DE");
|
||
<span class="strong"><strong>struct</strong></span> lconv *lc = <span class="strong"><strong>localeconv</strong></span>();
|
||
<span class="strong"><strong>if</strong></span> (<span class="strong"><strong>strcmp</strong></span>(lc->decimal_point, ",")) {
|
||
<span class="emphasis"><em>/* If decimal point is not a comma, presumably because the requested</em></span>
|
||
<span class="emphasis"><em> * locale was not available, report locale information. */</em></span>
|
||
<span class="strong"><strong>fprintf</strong></span>(stderr, "setlocale() returned '%s', decimal point is '%s'\n",
|
||
locname ? locname : "NULL",
|
||
lc->decimal_point);
|
||
}
|
||
|
||
FILE *file = <span class="strong"><strong>fopen</strong></span>(filename, "r");
|
||
<span class="strong"><strong>if</strong></span> (! file) {
|
||
<span class="strong"><strong>fprintf</strong></span>(stderr, "Cannot open %s file.\n", filename);
|
||
<span class="strong"><strong>exit</strong></span>(1);
|
||
}
|
||
|
||
<span class="emphasis"><em>/* An attribute table is needed to read graph attributes. */</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Attributes.html#igraph_set_attribute_table" title="1.2. igraph_set_attribute_table — Attach an attribute table.">igraph_set_attribute_table</a></strong></span>(&igraph_cattribute_table);
|
||
|
||
<span class="emphasis"><em>/* At this point, the current locale may use decimal commas.</em></span>
|
||
<span class="emphasis"><em> * We temporarily set a C locale using enter_safelocale() to</em></span>
|
||
<span class="emphasis"><em> * allow the GML reader and writer to work correctly.*/</em></span>
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_enter_safelocale" title="9.1. igraph_enter_safelocale — Temporarily set the C locale.">igraph_enter_safelocale</a></strong></span>(&loc);
|
||
<span class="strong"><strong>if</strong></span> (<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_read_graph_gml" title="4.1. igraph_read_graph_gml — Read a graph in GML format.">igraph_read_graph_gml</a></strong></span>(&graph, file) != IGRAPH_SUCCESS) {
|
||
<span class="strong"><strong>fprintf</strong></span>(stderr, "Reading %s failed.\n", filename);
|
||
<span class="strong"><strong>abort</strong></span>();
|
||
}
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_write_graph_gml" title="4.2. igraph_write_graph_gml — Write the graph to a stream in GML format.">igraph_write_graph_gml</a></strong></span>(&graph, stdout, IGRAPH_WRITE_GML_DEFAULT_SW, NULL, "");
|
||
<span class="strong"><strong><a class="link" href="igraph-Foreign.html#igraph_exit_safelocale" title="9.2. igraph_exit_safelocale — Temporarily set the C locale.">igraph_exit_safelocale</a></strong></span>(&loc);
|
||
|
||
<span class="strong"><strong><a class="link" href="igraph-Basic.html#igraph_destroy" title="5.1.4. igraph_destroy — Frees the memory allocated for a graph object.">igraph_destroy</a></strong></span>(&graph);
|
||
|
||
<span class="strong"><strong>return</strong></span> 0;
|
||
}
|
||
</pre>
|
||
<p></p>
|
||
</div>
|
||
</div>
|
||
<br class="example-break">
|
||
</div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="igraph_exit_safelocale"></a>9.2. <code class="function">igraph_exit_safelocale</code> — Temporarily set the C locale.</h3></div></div></div>
|
||
<a class="indexterm" name="id-1.32.13.3.2"></a><p>
|
||
</p>
|
||
<div class="informalexample"><pre class="programlisting">
|
||
void igraph_exit_safelocale(igraph_safelocale_t *loc);
|
||
</pre></div>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
|
||
|
||
|
||
Restores a locale saved by <a class="link" href="igraph-Foreign.html#igraph_enter_safelocale" title="9.1. igraph_enter_safelocale — Temporarily set the C locale."><code class="function">igraph_enter_safelocale()</code></a> and deallocates
|
||
all associated data. This function <span class="emphasis"><em>must</em></span> be paired with a call to
|
||
<a class="link" href="igraph-Foreign.html#igraph_enter_safelocale" title="9.1. igraph_enter_safelocale — Temporarily set the C locale."><code class="function">igraph_enter_safelocale()</code></a>.
|
||
|
||
</p>
|
||
<p><b>Arguments: </b>
|
||
</p>
|
||
<div class="variablelist"><table border="0" class="variablelist">
|
||
<colgroup>
|
||
<col align="left" valign="top">
|
||
<col>
|
||
</colgroup>
|
||
<tbody><tr>
|
||
<td><p><span class="term"><em class="parameter"><code>loc</code></em>:</span></p></td>
|
||
<td><p>
|
||
A variable of type <code class="constant">igraph_safelocale_t</code>, originally set
|
||
by <a class="link" href="igraph-Foreign.html#igraph_enter_safelocale" title="9.1. igraph_enter_safelocale — Temporarily set the C locale."><code class="function">igraph_enter_safelocale()</code></a>.</p></td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
<p>
|
||
|
||
|
||
</p>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<table class="navigation-footer" width="100%" summary="Navigation footer" cellpadding="2" cellspacing="0"><tr valign="middle">
|
||
<td align="left"><a accesskey="p" href="igraph-Processes.html"><b>← Chapter 30. Processes on graphs</b></a></td>
|
||
<td align="right"><a accesskey="n" href="igraph-Linalg.html"><b>Chapter 32. Using BLAS, LAPACK and ARPACK for igraph matrices and graphs →</b></a></td>
|
||
</tr></table>
|
||
</body>
|
||
</html>
|