line.graph(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.
# 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)))Run the code above in your browser using DataLab