ugraph {graph} | R Documentation |
For a directed graph the underlying graph is the graph that is
constructed where all edge orientation is ignored. This function
carries out such a transformation on graphNEL
instances.
ugraph(graph)
graph |
An instance of graphNEL . |
If graph
is already undirected then it is simply
returned.
If graph
is a multi-graph (has multiple edges) an error is
thrown as it is unclear how to compute the underlying graph in that
context.
An instance of graphNEL
with the same nodes as the input but
which is undirected
.
R. Gentleman
Graph Theory and its Applications, J. Gross and J. Yellen.
V <- letters[1:4] edL2 <- vector("list", length=4) names(edL2) <- V for(i in 1:4) edL2[[i]] <- list(edges=c(2,1,2,1)[i], weights=sqrt(i)) gR2 <- new("graphNEL", nodes=V, edgeL=edL2, edgemode="directed") ugraph(gR2)