Add graph references

2026-06-28 13:49:01 +01:00
parent 0a9807e448
commit a11edf0c53
2578 changed files with 868045 additions and 0 deletions
@@ -0,0 +1,153 @@
+/*
+   igraph library.
+   Copyright (C) 2006-2012  Gabor Csardi <csardi.gabor@gmail.com>
+   334 Harvard street, Cambridge, MA 02139 USA
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc.,  51 Franklin Street, Fifth Floor, Boston, MA
+   02110-1301 USA
+
+*/
+
+#include <igraph.h>
+
+igraph_bool_t handshaking_lemma(igraph_t *g, igraph_vector_int_t *v) {
+    /* Consistency check of the handshaking lemma:
+     * If d is the sum of all vertex degrees, then d = 2|E|. */
+    return igraph_vector_int_sum(v) == 2 * igraph_ecount(g);
+}
+
+int main(void) {
+    igraph_t g;
+    igraph_vector_int_t v;
+    igraph_vector_int_t seq;
+    igraph_int_t mdeg;
+
+    /* Initialize the library. */
+    igraph_setup();
+
+    /* Create graph */
+    igraph_vector_int_init(&v, 8);
+    igraph_small(&g, 4, IGRAPH_DIRECTED, 0,1, 1,2, 2,3, 2,2, -1);
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_OUT, IGRAPH_NO_LOOPS);
+    igraph_vector_int_print(&v);
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_OUT, IGRAPH_LOOPS);
+    igraph_vector_int_print(&v);
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_IN, IGRAPH_NO_LOOPS);
+    igraph_vector_int_print(&v);
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_IN, IGRAPH_LOOPS);
+    igraph_vector_int_print(&v);
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_ALL, IGRAPH_NO_LOOPS);
+    igraph_vector_int_print(&v);
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_ALL, IGRAPH_LOOPS);
+    igraph_vector_int_print(&v);
+
+    if (!handshaking_lemma(&g, &v)) {
+        exit(3);
+    }
+
+    igraph_destroy(&g);
+
+    igraph_small(&g, 4, IGRAPH_UNDIRECTED, 0,1, 1,2, 2,3, 2,2, -1);
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_OUT, IGRAPH_NO_LOOPS);
+    igraph_vector_int_print(&v);
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_OUT, IGRAPH_LOOPS);
+    igraph_vector_int_print(&v);
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_IN, IGRAPH_NO_LOOPS);
+    igraph_vector_int_print(&v);
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_IN, IGRAPH_LOOPS);
+    igraph_vector_int_print(&v);
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_ALL, IGRAPH_NO_LOOPS);
+    igraph_vector_int_print(&v);
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_ALL, IGRAPH_LOOPS);
+    igraph_vector_int_print(&v);
+
+    if (!handshaking_lemma(&g, &v)) {
+        exit(4);
+    }
+
+    /* Degree of the same vertex multiple times */
+
+    igraph_vector_int_init(&seq, 3);
+    VECTOR(seq)[0] = 2;
+    VECTOR(seq)[1] = 0;
+    VECTOR(seq)[2] = 2;
+    igraph_degree(&g, &v, igraph_vss_vector(&seq), IGRAPH_ALL, IGRAPH_LOOPS);
+    igraph_vector_int_print(&v);
+
+    igraph_destroy(&g);
+    igraph_vector_int_destroy(&seq);
+
+    /* Maximum degree */
+
+    igraph_ring(&g, 10, IGRAPH_UNDIRECTED, /* mutual */ false, /* circular */ false);
+    igraph_maxdegree(&g, &mdeg, igraph_vss_all(), IGRAPH_ALL, IGRAPH_LOOPS);
+    if (mdeg != 2) {
+        exit(5);
+    }
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_ALL, IGRAPH_LOOPS);
+    if (! handshaking_lemma(&g, &v)) {
+        exit(6);
+    }
+    igraph_destroy(&g);
+
+    igraph_full(&g, 10, IGRAPH_UNDIRECTED, IGRAPH_NO_LOOPS);
+    igraph_maxdegree(&g, &mdeg, igraph_vss_all(), IGRAPH_ALL, IGRAPH_LOOPS);
+    if (mdeg != 9) {
+        exit(7);
+    }
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_ALL, IGRAPH_LOOPS);
+    if (! handshaking_lemma(&g, &v)) {
+        exit(8);
+    }
+    igraph_destroy(&g);
+
+    igraph_star(&g, 10, IGRAPH_STAR_OUT, /* center */ 0);
+    igraph_maxdegree(&g, &mdeg, igraph_vss_all(), IGRAPH_OUT, IGRAPH_LOOPS);
+    if (mdeg != 9) {
+        exit(9);
+    }
+    igraph_maxdegree(&g, &mdeg, igraph_vss_all(), IGRAPH_IN, IGRAPH_LOOPS);
+    if (mdeg != 1) {
+        exit(10);
+    }
+    igraph_maxdegree(&g, &mdeg, igraph_vss_all(), IGRAPH_ALL, IGRAPH_LOOPS);
+    if (mdeg != 9) {
+        exit(11);
+    }
+
+    igraph_degree(&g, &v, igraph_vss_all(), IGRAPH_ALL, IGRAPH_LOOPS);
+    if (! handshaking_lemma(&g, &v)) {
+        exit(12);
+    }
+    igraph_destroy(&g);
+
+    igraph_vector_int_destroy(&v);
+
+    return 0;
+}