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


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

Iterate over edges in a breadth-first-search starting at source.

  • 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

edges – A generator of edges in the breadth-first-search.

Return type:



To get the edges in a breadth-first search:

>>> G = nx.path_graph(3)
>>> list(nx.bfs_edges(G, 0))
[(0, 1), (1, 2)]
>>> list(nx.bfs_edges(G, source=0, depth_limit=1))
[(0, 1)]

To get the nodes in a breadth-first search order:

>>> G = nx.path_graph(3)
>>> root = 2
>>> edges = nx.bfs_edges(G, root)
>>> nodes = [root] + [v for u, v in edges]
>>> nodes
[2, 1, 0]


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”.