dfs_edges#

dfs_edges(G, source=None, depth_limit=None, *, sort_neighbors=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.

sort_neighborsfunction (default=None)

A function that takes an iterator over nodes as the input, and returns an iterable of the same nodes with a custom ordering. For example, sorted will sort the nodes in increasing order.

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

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)]
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