Use this if you are using igraph from R
| is_igraph {igraph} | R Documentation | 
Is this object an igraph graph?
is_igraph(graph)
| graph | An R object. | 
A logical constant, TRUE if argument graph is a graph
object.
Gabor Csardi csardi.gabor@gmail.com
g <- make_ring(10)
is_igraph(g)
is_igraph(numeric(10))