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
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.
concept
Tree
Forest
Breadth-first search
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.