Mercurial > repos > guerler > springsuite
diff planemo/lib/python3.7/site-packages/networkx/algorithms/richclub.py @ 1:56ad4e20f292 draft
"planemo upload commit 6eee67778febed82ddd413c3ca40b3183a3898f1"
author | guerler |
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date | Fri, 31 Jul 2020 00:32:28 -0400 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/planemo/lib/python3.7/site-packages/networkx/algorithms/richclub.py Fri Jul 31 00:32:28 2020 -0400 @@ -0,0 +1,129 @@ +# -*- coding: utf-8 -*- +# Copyright (C) 2004-2019 by +# Aric Hagberg <hagberg@lanl.gov> +# Dan Schult <dschult@colgate.edu> +# Pieter Swart <swart@lanl.gov> +# All rights reserved. +# BSD license. +# +# Authors: Ben Edwards (bedwards@cs.unm.edu) +# Aric Hagberg (hagberg@lanl.gov) +"""Functions for computing rich-club coefficients.""" + +import networkx as nx +from networkx.utils import accumulate +from networkx.utils import not_implemented_for + +__all__ = ['rich_club_coefficient'] + + +@not_implemented_for('directed') +@not_implemented_for('multigraph') +def rich_club_coefficient(G, normalized=True, Q=100, seed=None): + r"""Returns the rich-club coefficient of the graph `G`. + + For each degree *k*, the *rich-club coefficient* is the ratio of the + number of actual to the number of potential edges for nodes with + degree greater than *k*: + + .. math:: + + \phi(k) = \frac{2 E_k}{N_k (N_k - 1)} + + where `N_k` is the number of nodes with degree larger than *k*, and + `E_k` is the number of edges among those nodes. + + Parameters + ---------- + G : NetworkX graph + Undirected graph with neither parallel edges nor self-loops. + normalized : bool (optional) + Normalize using randomized network as in [1]_ + Q : float (optional, default=100) + If `normalized` is True, perform `Q * m` double-edge + swaps, where `m` is the number of edges in `G`, to use as a + null-model for normalization. + seed : integer, random_state, or None (default) + Indicator of random number generation state. + See :ref:`Randomness<randomness>`. + + Returns + ------- + rc : dictionary + A dictionary, keyed by degree, with rich-club coefficient values. + + Examples + -------- + >>> G = nx.Graph([(0, 1), (0, 2), (1, 2), (1, 3), (1, 4), (4, 5)]) + >>> rc = nx.rich_club_coefficient(G, normalized=False) + >>> rc[0] # doctest: +SKIP + 0.4 + + Notes + ----- + The rich club definition and algorithm are found in [1]_. This + algorithm ignores any edge weights and is not defined for directed + graphs or graphs with parallel edges or self loops. + + Estimates for appropriate values of `Q` are found in [2]_. + + References + ---------- + .. [1] Julian J. McAuley, Luciano da Fontoura Costa, + and Tibério S. Caetano, + "The rich-club phenomenon across complex network hierarchies", + Applied Physics Letters Vol 91 Issue 8, August 2007. + https://arxiv.org/abs/physics/0701290 + .. [2] R. Milo, N. Kashtan, S. Itzkovitz, M. E. J. Newman, U. Alon, + "Uniform generation of random graphs with arbitrary degree + sequences", 2006. https://arxiv.org/abs/cond-mat/0312028 + """ + if nx.number_of_selfloops(G) > 0: + raise Exception('rich_club_coefficient is not implemented for ' + 'graphs with self loops.') + rc = _compute_rc(G) + if normalized: + # make R a copy of G, randomize with Q*|E| double edge swaps + # and use rich_club coefficient of R to normalize + R = G.copy() + E = R.number_of_edges() + nx.double_edge_swap(R, Q * E, max_tries=Q * E * 10, seed=seed) + rcran = _compute_rc(R) + rc = {k: v / rcran[k] for k, v in rc.items()} + return rc + + +def _compute_rc(G): + """Returns the rich-club coefficient for each degree in the graph + `G`. + + `G` is an undirected graph without multiedges. + + Returns a dictionary mapping degree to rich-club coefficient for + that degree. + + """ + deghist = nx.degree_histogram(G) + total = sum(deghist) + # Compute the number of nodes with degree greater than `k`, for each + # degree `k` (omitting the last entry, which is zero). + nks = (total - cs for cs in accumulate(deghist) if total - cs > 1) + # Create a sorted list of pairs of edge endpoint degrees. + # + # The list is sorted in reverse order so that we can pop from the + # right side of the list later, instead of popping from the left + # side of the list, which would have a linear time cost. + edge_degrees = sorted((sorted(map(G.degree, e)) for e in G.edges()), + reverse=True) + ek = G.number_of_edges() + k1, k2 = edge_degrees.pop() + rc = {} + for d, nk in enumerate(nks): + while k1 <= d: + if len(edge_degrees) == 0: + ek = 0 + break + k1, k2 = edge_degrees.pop() + ek -= 1 + rc[d] = 2 * ek / (nk * (nk - 1)) + return rc