Mercurial > repos > shellac > sam_consensus_v3
diff env/lib/python3.9/site-packages/networkx/algorithms/centrality/current_flow_betweenness_subset.py @ 0:4f3585e2f14b draft default tip
"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"
author | shellac |
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date | Mon, 22 Mar 2021 18:12:50 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/env/lib/python3.9/site-packages/networkx/algorithms/centrality/current_flow_betweenness_subset.py Mon Mar 22 18:12:50 2021 +0000 @@ -0,0 +1,228 @@ +"""Current-flow betweenness centrality measures for subsets of nodes.""" +import networkx as nx +from networkx.algorithms.centrality.flow_matrix import flow_matrix_row +from networkx.utils import not_implemented_for, reverse_cuthill_mckee_ordering + +__all__ = [ + "current_flow_betweenness_centrality_subset", + "edge_current_flow_betweenness_centrality_subset", +] + + +@not_implemented_for("directed") +def current_flow_betweenness_centrality_subset( + G, sources, targets, normalized=True, weight=None, dtype=float, solver="lu" +): + r"""Compute current-flow betweenness centrality for subsets of nodes. + + Current-flow betweenness centrality uses an electrical current + model for information spreading in contrast to betweenness + centrality which uses shortest paths. + + Current-flow betweenness centrality is also known as + random-walk betweenness centrality [2]_. + + Parameters + ---------- + G : graph + A NetworkX graph + + sources: list of nodes + Nodes to use as sources for current + + targets: list of nodes + Nodes to use as sinks for current + + normalized : bool, optional (default=True) + If True the betweenness values are normalized by b=b/(n-1)(n-2) where + n is the number of nodes in G. + + weight : string or None, optional (default=None) + Key for edge data used as the edge weight. + If None, then use 1 as each edge weight. + + dtype: data type (float) + Default data type for internal matrices. + Set to np.float32 for lower memory consumption. + + solver: string (default='lu') + Type of linear solver to use for computing the flow matrix. + Options are "full" (uses most memory), "lu" (recommended), and + "cg" (uses least memory). + + Returns + ------- + nodes : dictionary + Dictionary of nodes with betweenness centrality as the value. + + See Also + -------- + approximate_current_flow_betweenness_centrality + betweenness_centrality + edge_betweenness_centrality + edge_current_flow_betweenness_centrality + + Notes + ----- + Current-flow betweenness can be computed in $O(I(n-1)+mn \log n)$ + time [1]_, where $I(n-1)$ is the time needed to compute the + inverse Laplacian. For a full matrix this is $O(n^3)$ but using + sparse methods you can achieve $O(nm{\sqrt k})$ where $k$ is the + Laplacian matrix condition number. + + The space required is $O(nw)$ where $w$ is the width of the sparse + Laplacian matrix. Worse case is $w=n$ for $O(n^2)$. + + If the edges have a 'weight' attribute they will be used as + weights in this algorithm. Unspecified weights are set to 1. + + References + ---------- + .. [1] Centrality Measures Based on Current Flow. + Ulrik Brandes and Daniel Fleischer, + Proc. 22nd Symp. Theoretical Aspects of Computer Science (STACS '05). + LNCS 3404, pp. 533-544. Springer-Verlag, 2005. + http://algo.uni-konstanz.de/publications/bf-cmbcf-05.pdf + + .. [2] A measure of betweenness centrality based on random walks, + M. E. J. Newman, Social Networks 27, 39-54 (2005). + """ + from networkx.utils import reverse_cuthill_mckee_ordering + + try: + import numpy as np + except ImportError as e: + raise ImportError( + "current_flow_betweenness_centrality requires NumPy ", "http://numpy.org/" + ) from e + if not nx.is_connected(G): + raise nx.NetworkXError("Graph not connected.") + n = G.number_of_nodes() + ordering = list(reverse_cuthill_mckee_ordering(G)) + # make a copy with integer labels according to rcm ordering + # this could be done without a copy if we really wanted to + mapping = dict(zip(ordering, range(n))) + H = nx.relabel_nodes(G, mapping) + betweenness = dict.fromkeys(H, 0.0) # b[v]=0 for v in H + for row, (s, t) in flow_matrix_row(H, weight=weight, dtype=dtype, solver=solver): + for ss in sources: + i = mapping[ss] + for tt in targets: + j = mapping[tt] + betweenness[s] += 0.5 * np.abs(row[i] - row[j]) + betweenness[t] += 0.5 * np.abs(row[i] - row[j]) + if normalized: + nb = (n - 1.0) * (n - 2.0) # normalization factor + else: + nb = 2.0 + for v in H: + betweenness[v] = betweenness[v] / nb + 1.0 / (2 - n) + return {ordering[k]: v for k, v in betweenness.items()} + + +@not_implemented_for("directed") +def edge_current_flow_betweenness_centrality_subset( + G, sources, targets, normalized=True, weight=None, dtype=float, solver="lu" +): + r"""Compute current-flow betweenness centrality for edges using subsets + of nodes. + + Current-flow betweenness centrality uses an electrical current + model for information spreading in contrast to betweenness + centrality which uses shortest paths. + + Current-flow betweenness centrality is also known as + random-walk betweenness centrality [2]_. + + Parameters + ---------- + G : graph + A NetworkX graph + + sources: list of nodes + Nodes to use as sources for current + + targets: list of nodes + Nodes to use as sinks for current + + normalized : bool, optional (default=True) + If True the betweenness values are normalized by b=b/(n-1)(n-2) where + n is the number of nodes in G. + + weight : string or None, optional (default=None) + Key for edge data used as the edge weight. + If None, then use 1 as each edge weight. + + dtype: data type (float) + Default data type for internal matrices. + Set to np.float32 for lower memory consumption. + + solver: string (default='lu') + Type of linear solver to use for computing the flow matrix. + Options are "full" (uses most memory), "lu" (recommended), and + "cg" (uses least memory). + + Returns + ------- + nodes : dict + Dictionary of edge tuples with betweenness centrality as the value. + + See Also + -------- + betweenness_centrality + edge_betweenness_centrality + current_flow_betweenness_centrality + + Notes + ----- + Current-flow betweenness can be computed in $O(I(n-1)+mn \log n)$ + time [1]_, where $I(n-1)$ is the time needed to compute the + inverse Laplacian. For a full matrix this is $O(n^3)$ but using + sparse methods you can achieve $O(nm{\sqrt k})$ where $k$ is the + Laplacian matrix condition number. + + The space required is $O(nw)$ where $w$ is the width of the sparse + Laplacian matrix. Worse case is $w=n$ for $O(n^2)$. + + If the edges have a 'weight' attribute they will be used as + weights in this algorithm. Unspecified weights are set to 1. + + References + ---------- + .. [1] Centrality Measures Based on Current Flow. + Ulrik Brandes and Daniel Fleischer, + Proc. 22nd Symp. Theoretical Aspects of Computer Science (STACS '05). + LNCS 3404, pp. 533-544. Springer-Verlag, 2005. + http://algo.uni-konstanz.de/publications/bf-cmbcf-05.pdf + + .. [2] A measure of betweenness centrality based on random walks, + M. E. J. Newman, Social Networks 27, 39-54 (2005). + """ + try: + import numpy as np + except ImportError as e: + raise ImportError( + "current_flow_betweenness_centrality requires NumPy " "http://numpy.org/" + ) from e + if not nx.is_connected(G): + raise nx.NetworkXError("Graph not connected.") + n = G.number_of_nodes() + ordering = list(reverse_cuthill_mckee_ordering(G)) + # make a copy with integer labels according to rcm ordering + # this could be done without a copy if we really wanted to + mapping = dict(zip(ordering, range(n))) + H = nx.relabel_nodes(G, mapping) + edges = (tuple(sorted((u, v))) for u, v in H.edges()) + betweenness = dict.fromkeys(edges, 0.0) + if normalized: + nb = (n - 1.0) * (n - 2.0) # normalization factor + else: + nb = 2.0 + for row, (e) in flow_matrix_row(H, weight=weight, dtype=dtype, solver=solver): + for ss in sources: + i = mapping[ss] + for tt in targets: + j = mapping[tt] + betweenness[e] += 0.5 * np.abs(row[i] - row[j]) + betweenness[e] /= nb + return {(ordering[s], ordering[t]): v for (s, t), v in betweenness.items()}