spatstat.geom (version 2.1-0)

# edges2vees: 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.

## 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.

## 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 \(k\)th edge joins vertex `iedge[k]` to vertex `jedge[k]`. Entries of `iedge` and `jedge` must be integers from 1 to `nvert`.

## See Also

`edges2triangles`

## Examples

```# NOT RUN {
i <- c(1, 2, 5, 5, 1, 4, 2)
j <- c(2, 3, 3, 1, 3, 2, 5)
edges2vees(i, j)
# }
```