3.9. igraph_subisomorphic_function_vf2 — Generic VF2 function for subgraph isomorphism problems

3.9. `igraph_subisomorphic_function_vf2` — Generic VF2 function for subgraph isomorphism problems

int igraph_subisomorphic_function_vf2(const igraph_t *graph1, 
				      const igraph_t *graph2,
				      igraph_vector_t *map12,
				      igraph_vector_t *map21,
				      igraph_isohandler_t *function,
				      void *arg);

This function is the pair of igraph_isomorphic_function_vf2(), for subgraph isomorphism problems. It searches for subgraphs of graph1 which are isomorphic to graph2. When it founds an isomorphic mapping it calls the supplied callback function. The mapping (and its inverse) and the additional arg argument are supplied to the callback.

Arguments:

`graph1`:	The first input graph, may be directed or undirected. This is supposed to be the larger graph.
`graph2`:	The second input graph, it must have the same directedness as `graph1`. This is supposed to be the smaller graph.
`map12`:	Pointer to a vector or `NULL`. If not `NULL`, then an isomorphic mapping from `graph1` to `graph2` is stored here.
`map21`:	Pointer to a vector ot `NULL`. If not `NULL`, then an isomorphic mapping from `graph2` to `graph1` is stored here.
`function`:	A pointer to a function of type `igraph_isohandler_t`. This will be called whenever a subgraph isomorphism is found. If the function returns with a non-zero value then the search is continued, otherwise it stops and the function returns.
`arg`:	Extra argument to supply to the callback `function`.

Returns:

Error code.

Time complexity: exponential.