V {igraph} | R Documentation |

## Vertices of a graph

### Description

Create a vertex sequence (vs) containing all vertices of a graph.

### Usage

```
V(graph)
```

### Arguments

### Details

A vertex sequence is just what the name says it is: a sequence of
vertices. Vertex sequences are usually used as igraph function arguments
that refer to vertices of a graph.

A vertex sequence is tied to the graph it refers to: it really denoted
the specific vertices of that graph, and cannot be used together with
another graph.

At the implementation level, a vertex sequence is simply a vector
containing numeric vertex ids, but it has a special class attribute
which makes it possible to perform graph specific operations on it, like
selecting a subset of the vertices based on graph structure, or vertex
attributes.

A vertex sequence is most often created by the `V()`

function. The
result of this includes all vertices in increasing vertex id order. A
vertex sequence can be indexed by a numeric vector, just like a regular
R vector. See `[.igraph.vs`

and additional links to other
vertex sequence operations below.

### Value

A vertex sequence containing all vertices, in the order
of their numeric vertex ids.

### Indexing vertex sequences

Vertex sequences mostly behave like regular vectors, but there are some
additional indexing operations that are specific for them;
e.g. selecting vertices based on graph structure, or based on vertex
attributes. See `[.igraph.vs`

for details.

### Querying or setting attributes

Vertex sequences can be used to query or set attributes for the
vertices in the sequence. See `$.igraph.vs`

for details.

### See Also

Other vertex and edge sequences:
`E()`

,
`igraph-es-attributes`

,
`igraph-es-indexing2`

,
`igraph-es-indexing`

,
`igraph-vs-attributes`

,
`igraph-vs-indexing2`

,
`igraph-vs-indexing`

,
`print.igraph.es()`

,
`print.igraph.vs()`

### Examples

```
# Vertex ids of an unnamed graph
g <- make_ring(10)
V(g)
# Vertex ids of a named graph
g2 <- make_ring(10) %>%
set_vertex_attr("name", value = letters[1:10])
V(g2)
```

[Package

*igraph* version 1.3.4

Index]