networkx.algorithms.tree.recognition.is_tree

is_tree(G)[source]

Returns True if G is a tree.

A tree is a connected graph with no undirected cycles.

For directed graphs, G is a tree if the underlying graph is a tree. The underlying graph is obtained by treating each directed edge as a single undirected edge in a multigraph.

Parameters
Ggraph

The graph to test.

Returns
bbool

A boolean that is True if G is a tree.

See also

is_arborescence

Notes

In another convention, a directed tree is known as a polytree and then tree corresponds to an arborescence.