Warning

This documents an unmaintained version of NetworkX. Please upgrade to a maintained version and see the current NetworkX documentation.

networkx.algorithms.shortest_paths.unweighted.predecessor

predecessor(G, source, target=None, cutoff=None, return_seen=None)[source]

Returns dict of predecessors for the path from source to all nodes in G

Parameters

  • G (NetworkX graph)

  • source (node label) – Starting node for path

  • target (node label, optional) – Ending node for path. If provided only predecessors between source and target are returned

  • cutoff (integer, optional) – Depth to stop the search. Only paths of length <= cutoff are returned.

Returns

pred – Dictionary, keyed by node, of predecessors in the shortest path.

Return type

dictionary

Examples

>>> G = nx.path_graph(4)
>>> list(G)
[0, 1, 2, 3]
>>> nx.predecessor(G, 0)
{0: [], 1: [0], 2: [1], 3: [2]}