Create a vertex sequence (vs) containing all vertices of a 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.
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 f6808fe:
#> [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 3f9b868:
#> [1] a b c d e f g h i j