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 yield edges in the component reachable from source.
depth_limitint, optional (default=len(G)): Specify the maximum search depth.

Yields

edge: 2-tuple of nodes: Yields edges resulting from the depth-first-search.

See also

dfs_preorder_nodes
dfs_postorder_nodes
dfs_labeled_edges
edge_dfs()
bfs_edges()

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 [1], with modifications to allow depth limits based on the Wikipedia article “Depth-limited search” [2].

References

1: http://www.ics.uci.edu/~eppstein/PADS
2: https://en.wikipedia.org/wiki/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)]