Use this if you are using igraph from R
Concatenate vertex sequences
## S3 method for class 'igraph.vs' c(..., recursive = FALSE)
The vertex sequences to concatenate. They must refer to the same graph.
Ignored, included for S3 compatibility with
A vertex sequence, the input sequences concatenated.
Other vertex and edge sequence operations:
g <- make_(ring(10), with_vertex_(name = LETTERS[1:10])) c(V(g), V(g)['A'], V(g)[1:4])