networkx.algorithms.traversal.depth_first_search.dfs_predecessors¶
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dfs_predecessors
(G, source=None, depth_limit=None)[source]¶ Return dictionary of predecessors in depth-first-search from source.
Parameters: - G (NetworkX graph)
- source (node, optional) – Specify starting node for depth-first search and return edges in the component reachable from source.
- depth_limit (int, optional (default=len(G))) – Specify the maximum search depth.
Returns: pred – A dictionary with nodes as keys and predecessor nodes as values.
Return type: Examples
>>> G = nx.path_graph(4) >>> nx.dfs_predecessors(G, source=0) {1: 0, 2: 1, 3: 2} >>> nx.dfs_predecessors(G, source=0, depth_limit=2) {1: 0, 2: 1}
Notes
If a source is not specified then a source is chosen arbitrarily and repeatedly until all components in the graph are searched.
The implementation of this function is adapted from David Eppstein’s depth-first search function in PADS, with modifications to allow depth limits based on the Wikipedia article “Depth-limited search”.