Note

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

networkx.algorithms.traversal.depth_first_search.dfs_preorder_nodes

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

Generate nodes in a depth-first-search pre-ordering starting at source.

Parameters
  • G (NetworkX graph)

  • source (node, optional) – Specify starting node for depth-first search and return nodes in the component reachable from source.

  • depth_limit (int, optional (default=len(G))) – Specify the maximum search depth.

Returns

nodes – A generator of nodes in a depth-first-search pre-ordering.

Return type

generator

Examples

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

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”.