line.graph {igraph}R Documentation

Line graph of a graph

Description

This function calculates the line graph of another graph.

Usage

line.graph(graph)

Arguments

graph

The input graph, it can be directed or undirected.

Details

The line graph L(G) of a G undirected graph is defined as follows. L(G) has one vertex for each edge in G and two vertices in L(G) are connected by an edge if their corresponding edges share an end point.

The line graph L(G) of a G directed graph is slightly different, L(G) has one vertex for each edge in G and two vertices in L(G) are connected by a directed edge if the target of the first vertex's corresponding edge is the same as the source of the second vertex's corresponding edge.

Value

A new graph object.

Author(s)

Gabor Csardi csardi@rmki.kfki.hu, the first version of the C code was written by Vincent Matossian.

Examples

# generate the first De-Bruijn graphs
g <- graph.full(2, directed=TRUE, loops=TRUE)
line.graph(g)
line.graph(line.graph(g))
line.graph(line.graph(line.graph(g)))

[Package igraph version 0.5.5-4 Index]