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networkx.algorithms.traversal.breadth_first_search.bfs_tree

bfs_tree(G, source, reverse=False, depth_limit=None)[source]

Return an oriented tree constructed from of a breadth-first-search starting at source.

Parameters:
  • G (NetworkX graph)
  • source (node) – Specify starting node for breadth-first search and return edges in the component reachable from source.
  • reverse (bool, optional) – If True traverse a directed graph in the reverse direction
  • depth_limit (int, optional(default=len(G))) – Specify the maximum search depth
Returns:

T – An oriented tree
Return type:

NetworkX DiGraph

Examples

>>> G = nx.path_graph(3)
>>> print(list(nx.bfs_tree(G,1).edges()))
[(1, 0), (1, 2)]
>>> H = nx.Graph()
>>> nx.add_path(H, [0, 1, 2, 3, 4, 5, 6])
>>> nx.add_path(H, [2, 7, 8, 9, 10])
>>> print(sorted(list(nx.bfs_tree(H, source=3, depth_limit=3).edges())))
[(1, 0), (2, 1), (2, 7), (3, 2), (3, 4), (4, 5), (5, 6), (7, 8)]

Notes

Based on http://www.ics.uci.edu/~eppstein/PADS/BFS.py by D. Eppstein, July 2004. The modifications to allow depth limits based on the Wikipedia article “Depth-limited-search”.