bfs_edges(G, source, reverse=False, depth_limit=None, sort_neighbors=None)¶
Iterate over edges in a breadth-first-search starting at source.
G (NetworkX graph)
source (node) – Specify starting node for breadth-first search; this function iterates over only those edges in the component reachable from this node.
reverse (bool, optional) – If True traverse a directed graph in the reverse direction
depth_limit (int, optional(default=len(G))) – Specify the maximum search depth
sort_neighbors (function) – A function that takes the list of neighbors of given node as input, and returns an iterator over these neighbors but with custom ordering.
edges – A generator of edges in the breadth-first-search.
- Return type
To get the edges in a breadth-first search:
>>> G = nx.path_graph(3) >>> list(nx.bfs_edges(G, 0)) [(0, 1), (1, 2)] >>> list(nx.bfs_edges(G, source=0, depth_limit=1)) [(0, 1)]
To get the nodes in a breadth-first search order:
>>> G = nx.path_graph(3) >>> root = 2 >>> edges = nx.bfs_edges(G, root) >>> nodes = [root] + [v for u, v in edges] >>> nodes [2, 1, 0]
The naming of this function is very similar to edge_bfs. The difference is that ‘edge_bfs’ yields edges even if they extend back to an already explored node while ‘bfs_edges’ yields the edges of the tree that results from a breadth-first-search (BFS) so no edges are reported if they extend to already explored nodes. That means ‘edge_bfs’ reports all edges while ‘bfs_edges’ only reports those traversed by a node-based BFS. Yet another description is that ‘bfs_edges’ reports the edges traversed during BFS while ‘edge_bfs’ reports all edges in the order they are explored.