edges2vees: List Dihedral Triples in a Graph

In spatstat.geom: Geometrical Functionality of the 'spatstat' Family

List Dihedral Triples in a Graph

Description

Given a list of edges between vertices, compile a list of all ‘vees’ or dihedral triples formed by these edges.

Usage

edges2vees(iedge, jedge, nvert=max(iedge, jedge), ...,
                check=TRUE)

Arguments

iedge,jedge	Integer vectors, of equal length, specifying the edges.
nvert	Number of vertices in the network.
...	Ignored
check	Logical. Whether to check validity of input data.

Details

Given a finite graph with nvert vertices and with edges specified by iedge, jedge, this low-level function finds all ‘vees’ or ‘dihedral triples’ in the graph, that is, all triples of vertices (i,j,k) where i and j are joined by an edge and i and k are joined by an edge.

The interpretation of iedge, jedge is that each successive pair of entries specifies an edge in the graph. The kth edge joins vertex iedge[k] to vertex jedge[k]. Entries of iedge and jedge must be integers from 1 to nvert.

Value

A 3-column matrix of integers, in which each row represents a triple of vertices, with the first vertex joined to the other two vertices.

Author(s)

\adrian

and \rolf

See Also

edges2triangles

Examples

 i <- c(1, 2, 5, 5, 1, 4, 2)
 j <- c(2, 3, 3, 1, 3, 2, 5)
 edges2vees(i, j)

spatstat.geom documentation built on Oct. 20, 2023, 9:06 a.m.