5.1. igraph_vit_create — Creates a vertex iterator from a vertex selector.

5.1. `igraph_vit_create` — Creates a vertex iterator from a vertex selector.

int igraph_vit_create(const igraph_t *graph, 
		      igraph_vs_t vs, igraph_vit_t *vit);

This function instantiates a vertex selector object with a given graph. This is the step when the actual vertex ids are created from the logical notion of the vertex selector based on the graph. Eg. a vertex selector created with igraph_vs_all() contains knowledge that all vertices are included in a (yet indefinite) graph. When instantiating it a vertex iterator object is created, this contains the actual vertex ids in the graph supplied as a parameter.

The same vertex selector object can be used to instantiate any number vertex iterators.

Arguments:

`graph`:	An igraph_t object, a graph.
`vs`:	A vertex selector object.
`vit`:	Pointer to an uninitialized vertex iterator object.

Returns:

Error code.

See also:

igraph_vit_destroy().

Time complexity: it depends on the vertex selector type. O(1) for vertex selectors created with igraph_vs_all(), igraph_vs_none(), igraph_vs_1, igraph_vs_vector, igraph_vs_seq(), igraph_vs_vector(), igraph_vs_vector_small(). O(d) for igraph_vs_adj(), d is the number of vertex ids to be included in the iterator. O(|V|) for igraph_vs_nonadj(), |V| is the number of vertices in the graph.