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Source code for networkx.algorithms.approximation.clustering_coefficient

# -*- coding: utf-8 -*-
#   Copyright (C) 2013 by
#   Fred Morstatter <fred.morstatter@asu.edu>
#   Jordi Torrents <jtorrents@milnou.net>
#   All rights reserved.
#   BSD license.
import random
from networkx.utils import not_implemented_for

__all__ = ['average_clustering']
__author__ = """\n""".join(['Fred Morstatter <fred.morstatter@asu.edu>',
                            'Jordi Torrents <jtorrents@milnou.net>'])

[docs]def average_clustering(G, trials=1000): r"""Estimates the average clustering coefficient of G. The local clustering of each node in `G` is the fraction of triangles that actually exist over all possible triangles in its neighborhood. The average clustering coefficient of a graph `G` is the mean of local clusterings. This function finds an approximate average clustering coefficient for G by repeating `n` times (defined in `trials`) the following experiment: choose a node at random, choose two of its neighbors at random, and check if they are connected. The approximate coefficient is the fraction of triangles found over the number of trials [1]_. Parameters ---------- G : NetworkX graph trials : integer Number of trials to perform (default 1000). Returns ------- c : float Approximated average clustering coefficient. References ---------- .. [1] Schank, Thomas, and Dorothea Wagner. Approximating clustering coefficient and transitivity. Universität Karlsruhe, Fakultät für Informatik, 2004. http://www.emis.ams.org/journals/JGAA/accepted/2005/SchankWagner2005.9.2.pdf """ n = len(G) triangles = 0 nodes = G.nodes() for i in [int(random.random() * n) for i in range(trials)]: nbrs = list(G[nodes[i]]) if len(nbrs) < 2: continue u, v = random.sample(nbrs, 2) if u in G[v]: triangles += 1 return triangles / float(trials)