Basic query operations to get adjacency

Basic query operations to get adjacency

Usage

edge(graph, eid)

edges(graph, eids = integer(0), bycol = FALSE)

get_eids(graph, edges, directed = is_directed(graph), error = TRUE)

get_all_eids_between(graph, from, to, directed = is_directed(graph))

neighbors(graph, vid, mode = 3L, loops = 1L, multiple = TRUE)

incident(graph, vid, mode = 3L, loops = 1L)

degree(graph, vids = integer(0), mode = 3L, loops = 1L)

Source

https://igraph.org/c/doc/igraph-Basic.html#basic-query-operations

Arguments

graph

An igraph_ptr object.

eid

An integer value of edge ID.

eids

An integer vector of edge IDs.

bycol

A logical value to specify the result format. If FALSE (default), the result is an edge list compatible with add_edges(). If TRUE, the result is suitable for making a 2-column matrix as returned by as.matrix.igraph_ptr().

edges

An integer vector of vertex IDs; the first two elements are the first edge, etc.

directed

A logical value, whether to consider directed paths. Ignored for undirected graphs.

error

A logical value, whether to raise an error or assign 0 for non-existing edges.

from

An integer vector of vertex IDs.

to

An integer vector of vertex IDs.

vid

An integer value of vertex ID.

mode

An integer value of edge type to count; {1: OUT, 2: IN, 3: ALL}.

loops

whether self-loop should be counted.

multiple

A logical value, whether to keep multiple (parallel) edges.

vids

An integer vector of vertex IDs.

Value

edge() and edges() return the head and tail vertices of edges.

get_eids() returns the edge IDs of given vertex pairs.

get_all_eids_between() returns all edge IDs between two vertices.

neighbors() returns the adjacent vertices to a vertex.

incident() returns the incident edges of a vertex.

degree() returns the degrees of vertices in a graph.

See also

as_adjlist() and as_inclist() for the all-vertices version of neighbors() and incident().

is_sink(), is_source(), Vsink(), Vsource() for shortcuts to get zero-degree vertices.

Examples

g = graph_tree(5L)
edge(g, 1L)
#> [1] 1 2

edges(g, c(1L, 3L))
#> [1] 1 2 2 4

get_eids(g, c(1L, 2L, 2L, 4L))
#> [1] 1 3

get_all_eids_between(g, 1L, 2L)
#> [1] 1

neighbors(g, 1L)
#> [1] 2 3

incident(g, 1L)
#> [1] 1 2

degree(g, mode = 1L)
#> [1] 2 2 0 0 0

degree(g, mode = 2L)
#> [1] 0 1 1 1 1

degree(g, mode = 3L)
#> [1] 2 3 1 1 1