# count_isomorphisms

##### Count the number of isomorphic mappings between two graphs

Count the number of isomorphic mappings between two graphs

##### Usage

`count_isomorphisms(graph1, graph2, method = "vf2", ...)`

##### Arguments

- graph1
- The first graph.
- graph2
- The second graph.
- method
- Currently only
vf2 is supported, see`isomorphic`

for details about it and extra arguments. - ...
- Passed to the individual methods.

##### Value

- Number of isomirphic mappings between the two graphs.

##### References

LP Cordella, P Foggia, C Sansone, and M Vento: An improved algorithm
for matching large graphs, *Proc. of the 3rd IAPR TC-15 Workshop
on Graphbased Representations in Pattern Recognition*, 149--159, 2001.

##### See Also

Other graph isomorphism: `count_subgraph_isomorphisms`

,
`graph.count.subisomorphisms.vf2`

;
`graph.get.isomorphisms.vf2`

,
`isomorphisms`

;
`graph.get.subisomorphisms.vf2`

,
`subgraph_isomorphisms`

;
`graph.isoclass`

,
`graph.isoclass.subgraph`

,
`isomorphism_class`

;
`graph.isocreate`

,
`graph_from_isomorphism_class`

;
`graph.isomorphic`

,
`graph.isomorphic.34`

,
`graph.isomorphic.bliss`

,
`graph.isomorphic.vf2`

,
`is_isomorphic_to`

, `isomorphic`

;
`graph.subisomorphic.lad`

,
`graph.subisomorphic.vf2`

,
`is_subgraph_isomorphic_to`

,
`subgraph_isomorphic`

##### Examples

```
# colored graph isomorphism
g1 <- make_ring(10)
g2 <- make_ring(10)
isomorphic(g1, g2)
V(g1)$color <- rep(1:2, length = vcount(g1))
V(g2)$color <- rep(2:1, length = vcount(g2))
# consider colors by default
count_isomorphisms(g1, g2)
# ignore colors
count_isomorphisms(g1, g2, vertex.color1 = NULL,
vertex.color2 = NULL)
```

*Documentation reproduced from package igraph, version 1.0.0, License: GPL (>= 2)*