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 f
roots
A vector giving the vertices from which the breadth-first
search is performed. Typically it contains one vertex per component.
Value
A list with two components:
treeThe result, an igraph
object, a tree or a forest.
vertex_indexA numeric vector, it gives
a mapping from the vertices of the new graph to the vertices of the old
graph.
Details
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.