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This documents an unmaintained version of NetworkX. Please upgrade to a maintained version and see the current NetworkX documentation.

Source code for networkx.algorithms.vitality

"""
Vitality measures.
"""
#    Copyright (C) 2012 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(['Aric Hagberg (hagberg@lanl.gov)',
                        'Renato Fabbri'])
__all__ = ['closeness_vitality']

def weiner_index(G, weight=None):
    # compute sum of distances between all node pairs
    # (with optional weights)
    weiner=0.0
    if weight is None:
        for n in G:
            path_length=nx.single_source_shortest_path_length(G,n)
            weiner+=sum(path_length.values())
    else:
        for n in G:
            path_length=nx.single_source_dijkstra_path_length(G,
                    n,weight=weight)
            weiner+=sum(path_length.values())
    return weiner


[docs]def closeness_vitality(G, weight=None): """Compute closeness vitality for nodes. Closeness vitality of a node is the change in the sum of distances between all node pairs when excluding that node. Parameters ---------- G : graph weight : None or string (optional) The name of the edge attribute used as weight. If None the edge weights are ignored. Returns ------- nodes : dictionary Dictionary with nodes as keys and closeness vitality as the value. Examples -------- >>> G=nx.cycle_graph(3) >>> nx.closeness_vitality(G) {0: 4.0, 1: 4.0, 2: 4.0} See Also -------- closeness_centrality() References ---------- .. [1] Ulrik Brandes, Sec. 3.6.2 in Network Analysis: Methodological Foundations, Springer, 2005. http://books.google.com/books?id=TTNhSm7HYrIC """ multigraph = G.is_multigraph() wig = weiner_index(G,weight) closeness_vitality = {} for n in G: # remove edges connected to node n and keep list of edges with data # could remove node n but it doesn't count anyway if multigraph: edges = G.edges(n,data=True,keys=True) if G.is_directed(): edges += G.in_edges(n,data=True,keys=True) else: edges = G.edges(n,data=True) if G.is_directed(): edges += G.in_edges(n,data=True) G.remove_edges_from(edges) closeness_vitality[n] = wig - weiner_index(G,weight) # add edges and data back to graph G.add_edges_from(edges) return closeness_vitality