Use this if you are using igraph from R
Perform a breadth-first search on a graph and convert it into a tree or forest by replicating vertices that were found more than once.
unfold_tree(graph, mode = c("all", "out", "in", "total"), roots)
graph |
The input graph, it can be either directed or undirected. |
mode |
Character string, defined the types of the paths used for the breadth-first search. “out” follows the outgoing, “in” the incoming edges, “all” and “total” both of them. This argument is ignored for undirected graphs. |
roots |
A vector giving the vertices from which the breadth-first search is performed. Typically it contains one vertex per component. |
A forest is a graph, whose components are trees.
The roots
vector can be calculated by simply doing a topological sort
in all components of the graph, see the examples below.
A list with two components:
tree |
The result, an |
vertex_index |
A numeric vector, it gives a mapping from the vertices of the new graph to the vertices of the old graph. |
Gabor Csardi csardi.gabor@gmail.com
g <- make_tree(10) %du% make_tree(10) V(g)$id <- seq_len(vcount(g))-1 roots <- sapply(decompose(g), function(x) { V(x)$id[ topo_sort(x)[1]+1 ] }) tree <- unfold_tree(g, roots=roots)