networkx.algorithms.lowest_common_ancestors.lowest_common_ancestor¶

lowest_common_ancestor(G, node1, node2, default=None)[source]¶

Compute the lowest common ancestor of the given pair of nodes.

Parameters

G (NetworkX directed graph)
node1, node2 (nodes in the graph.)
default (object) – Returned if no common ancestor between node1 and node2

Returns

The lowest common ancestor of node1 and node2,
or default if they have no common ancestors.

Notes

Only defined on non-null directed acyclic graphs. Takes n log(n) time in the size of the graph. See all_pairs_lowest_common_ancestor when you have more than one pair of nodes of interest.