# union.igraph.vs

##### Union of vertex sequences

Union of vertex sequences

##### Usage

```
# S3 method for igraph.vs
union(...)
```

##### Arguments

- ...
The vertex sequences to take the union of.

##### Details

They must belong to the same graph. Note that this function has
‘set’ semantics and the multiplicity of vertices is lost in the
result. (This is to match the behavior of the based `unique`

function.)

##### Value

A vertex sequence that contains all vertices in the given sequences, exactly once.

##### See Also

Other vertex and edge sequence operations: `[.igraph.es`

,
`%--%`

, `%->%`

,
`%<-%`

, `igraph-es-indexing`

;
`[.igraph.vs`

,
`igraph-vs-indexing`

;
`[[.igraph.es`

,
`igraph-es-indexing2`

;
`[[.igraph.vs`

,
`igraph-vs-indexing2`

;
`c.igraph.es`

; `c.igraph.vs`

;
`difference.igraph.es`

;
`difference.igraph.vs`

;
`intersection.igraph.es`

;
`intersection.igraph.vs`

;
`rev.igraph.es`

; `rev.igraph.vs`

;
`union.igraph.es`

;
`unique.igraph.es`

;
`unique.igraph.vs`

##### Examples

```
# NOT RUN {
g <- make_(ring(10), with_vertex_(name = LETTERS[1:10]))
union(V(g)[1:6], V(g)[5:10])
# }
```

*Documentation reproduced from package igraph, version 1.0.1, License: GPL (>= 2)*