| """ |
| Ego graph. |
| """ |
| # Copyright (C) 2010 by |
| # Aric Hagberg <hagberg@lanl.gov> |
| # Dan Schult <dschult@colgate.edu> |
| # Pieter Swart <swart@lanl.gov> |
| # All rights reserved. |
| # BSD license. |
| __author__ = """\n""".join(['Drew Conway <drew.conway@nyu.edu>', |
| 'Aric Hagberg <hagberg@lanl.gov>']) |
| __all__ = ['ego_graph'] |
| |
| import networkx as nx |
| |
| def ego_graph(G,n,radius=1,center=True,undirected=False,distance=None): |
| """Returns induced subgraph of neighbors centered at node n within |
| a given radius. |
| |
| Parameters |
| ---------- |
| G : graph |
| A NetworkX Graph or DiGraph |
| |
| n : node |
| A single node |
| |
| radius : number, optional |
| Include all neighbors of distance<=radius from n. |
| |
| center : bool, optional |
| If False, do not include center node in graph |
| |
| undirected : bool, optional |
| If True use both in- and out-neighbors of directed graphs. |
| |
| distance : key, optional |
| Use specified edge data key as distance. For example, setting |
| distance='weight' will use the edge weight to measure the |
| distance from the node n. |
| |
| Notes |
| ----- |
| For directed graphs D this produces the "out" neighborhood |
| or successors. If you want the neighborhood of predecessors |
| first reverse the graph with D.reverse(). If you want both |
| directions use the keyword argument undirected=True. |
| |
| Node, edge, and graph attributes are copied to the returned subgraph. |
| """ |
| if undirected: |
| if distance is not None: |
| sp,_=nx.single_source_dijkstra(G.to_undirected(), |
| n,cutoff=radius, |
| weight=distance) |
| else: |
| sp=nx.single_source_shortest_path_length(G.to_undirected(), |
| n,cutoff=radius) |
| else: |
| if distance is not None: |
| sp,_=nx.single_source_dijkstra(G, |
| n,cutoff=radius, |
| weight=distance) |
| else: |
| sp=nx.single_source_shortest_path_length(G,n,cutoff=radius) |
| |
| H=G.subgraph(sp).copy() |
| if not center: |
| H.remove_node(n) |
| return H |
