Note

This documents the development version of NetworkX. Documentation for the current release can be found here.

networkx.algorithms.traversal.depth_first_search.dfs_edges

dfs_edges(G, source=None, depth_limit=None)[source]

Iterate over edges in a depth-first-search (DFS).

Perform a depth-first-search over the nodes of G and yield the edges in order. This may not generate all edges in G (see edge_dfs).

Parameters
GNetworkX graph
sourcenode, optional

Specify starting node for depth-first search and return edges in the component reachable from source.

depth_limitint, optional (default=len(G))

Specify the maximum search depth.

Returns
edges: generator

A generator of edges in the depth-first-search.

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”.

Examples

>>> G = nx.path_graph(5)
>>> list(nx.dfs_edges(G, source=0))
[(0, 1), (1, 2), (2, 3), (3, 4)]
>>> list(nx.dfs_edges(G, source=0, depth_limit=2))
[(0, 1), (1, 2)]