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

## Usage

``V(graph)``

graph

The graph

## Value

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

## 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.

## 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()`, `as_ids()`, `igraph-es-attributes`, `igraph-es-indexing`, `igraph-es-indexing2`, `igraph-vs-attributes`, `igraph-vs-indexing`, `igraph-vs-indexing2`, `print.igraph.es()`, `print.igraph.vs()`

## Examples

``````# Vertex ids of an unnamed graph
g <- make_ring(10)
V(g)
#> + 10/10 vertices, from 4e04d00:
#>  [1]  1  2  3  4  5  6  7  8  9 10

# Vertex ids of a named graph
g2 <- make_ring(10) %>%
set_vertex_attr("name", value = letters[1:10])
V(g2)
#> + 10/10 vertices, named, from 9d848b6:
#>  [1] a b c d e f g h i j
``````