Use this if you are using igraph from R
Remove duplicate vertices from a vertex sequence
## S3 method for class 'igraph.vs' unique(x, incomparables = FALSE, ...)
| x | A vertex sequence. | 
| incomparables | a vector of values that cannot be compared.
Passed to base function  | 
| ... | Passed to base function  | 
A vertex sequence with the duplicate vertices removed.
Other vertex and edge sequence operations: 
c.igraph.es(),
c.igraph.vs(),
difference.igraph.es(),
difference.igraph.vs(),
igraph-es-indexing2,
igraph-es-indexing,
igraph-vs-indexing2,
igraph-vs-indexing,
intersection.igraph.es(),
intersection.igraph.vs(),
rev.igraph.es(),
rev.igraph.vs(),
union.igraph.es(),
union.igraph.vs(),
unique.igraph.es()
g <- make_(ring(10), with_vertex_(name = LETTERS[1:10])) V(g)[1, 1:5, 1:10, 5:10] V(g)[1, 1:5, 1:10, 5:10] %>% unique()