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:

GNetworkX graph
sourcenode, optional: Specify starting node for depth-first search and return nodes in the component reachable from source.
depth_limitint, optional (default=len(G)): Specify the maximum search depth.

Returns:

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

See also

dfs_edges
dfs_postorder_nodes
dfs_labeled_edges
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, with modifications to allow depth limits based on the Wikipedia article “Depth-limited search”.

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]