R: Vertices of a graph

V {igraph} | R Documentation

## Vertices of a graph

### Description

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

### Usage

    V(graph)

### Arguments

`graph` | The graph

### 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 1.3.1 Index]