No vertices, undirected:
[ 0-by-0 ]
No vertices, directed:
[ 0-by-0 ]
No edges, undirected:
[        0      Inf      Inf
       Inf        0      Inf
       Inf      Inf        0 ]
No edges, directed:
[        0      Inf      Inf      Inf
       Inf        0      Inf      Inf
       Inf      Inf        0      Inf
       Inf      Inf      Inf        0 ]
Directed graph with loops and multi-edges:
[        0       -1       -3        1        6      Inf
         1        0       -2        2        7      Inf
         3        2        0        4        9      Inf
       Inf      Inf      Inf        0        5      Inf
       Inf      Inf      Inf      Inf        0      Inf
       Inf      Inf      Inf      Inf      Inf        0 ]
Directed graph with loops and multi-edges, select vertices 1 and 2:
[        0       -2
         2        0 ]
Directed graph with loops and multi-edges, select 0 -> 2:
[       -3 ]
Directed graph with loops and multi-edges, select none:
[ 0-by-0 ]
Directed graph with loops and multi-edges, IGRAPH_IN:
[        0        1        3      Inf      Inf      Inf
        -1        0        2      Inf      Inf      Inf
        -3       -2        0      Inf      Inf      Inf
         1        2        4        0      Inf      Inf
         6        7        9        5        0      Inf
       Inf      Inf      Inf      Inf      Inf        0 ]
Checking error for directed graph with loops and multi-edges with negative loop.
Directed graph with loops and multi-edges, IGRAPH_ALL:
