| # encoding: utf-8 |
| """ |
| Functions for identifying isolate (degree zero) nodes. |
| """ |
| # Copyright (C) 2004-2011 by |
| # Aric Hagberg <hagberg@lanl.gov> |
| # Dan Schult <dschult@colgate.edu> |
| # Pieter Swart <swart@lanl.gov> |
| # All rights reserved. |
| # BSD license. |
| import networkx as nx |
| __author__ = """\n""".join(['Drew Conway <drew.conway@nyu.edu>', |
| 'Aric Hagberg <hagberg@lanl.gov>']) |
| __all__=['is_isolate','isolates'] |
| |
| def is_isolate(G,n): |
| """Determine of node n is an isolate (degree zero). |
| |
| Parameters |
| ---------- |
| G : graph |
| A networkx graph |
| n : node |
| A node in G |
| |
| Returns |
| ------- |
| isolate : bool |
| True if n has no neighbors, False otherwise. |
| |
| Examples |
| -------- |
| >>> G=nx.Graph() |
| >>> G.add_edge(1,2) |
| >>> G.add_node(3) |
| >>> nx.is_isolate(G,2) |
| False |
| >>> nx.is_isolate(G,3) |
| True |
| """ |
| return G.degree(n)==0 |
| |
| def isolates(G): |
| """Return list of isolates in the graph. |
| |
| Isolates are nodes with no neighbors (degree zero). |
| |
| Parameters |
| ---------- |
| G : graph |
| A networkx graph |
| |
| Returns |
| ------- |
| isolates : list |
| List of isolate nodes. |
| |
| Examples |
| -------- |
| >>> G = nx.Graph() |
| >>> G.add_edge(1,2) |
| >>> G.add_node(3) |
| >>> nx.isolates(G) |
| [3] |
| |
| To remove all isolates in the graph use |
| >>> G.remove_nodes_from(nx.isolates(G)) |
| >>> G.nodes() |
| [1, 2] |
| |
| For digraphs isolates have zero in-degree and zero out_degre |
| >>> G = nx.DiGraph([(0,1),(1,2)]) |
| >>> G.add_node(3) |
| >>> nx.isolates(G) |
| [3] |
| """ |
| return [n for (n,d) in G.degree_iter() if d==0] |
