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1 | /* | |
2 | * Copyright (c) 2003, the JUNG Project and the Regents of the University | |
3 | * of California | |
4 | * All rights reserved. | |
5 | * | |
6 | * This software is open-source under the BSD license; see either | |
7 | * "license.txt" or | |
8 | * http://jung.sourceforge.net/license.txt for a description. | |
9 | */ | |
10 | package edu.uci.ics.jung.algorithms.cluster; | |
11 | ||
12 | import java.util.*; | |
13 | ||
14 | import cern.colt.list.DoubleArrayList; | |
15 | import cern.jet.stat.Descriptive; | |
16 | import edu.uci.ics.jung.algorithms.flows.EdmondsKarpMaxFlow; | |
17 | import edu.uci.ics.jung.graph.*; | |
18 | import edu.uci.ics.jung.graph.decorators.NumericDecorator; | |
19 | import edu.uci.ics.jung.graph.impl.SparseVertex; | |
20 | import edu.uci.ics.jung.statistics.DegreeDistributions; | |
21 | import edu.uci.ics.jung.utils.GraphUtils; | |
22 | import edu.uci.ics.jung.utils.MutableInteger; | |
23 | import edu.uci.ics.jung.utils.UserData; | |
24 | ||
25 | /** | |
26 | * ExactFlowCommunity is an algorithm that uses a set of root nodes that are | |
27 | * supposed to be representative of a community to find the entire community | |
28 | * using principles based on max-flow/min-cut. | |
29 | * @author Scott White | |
30 | * @see "Self-Organization of the Web and Identification of Communities by Gary | |
31 | * Flake, Steve Lawrence, Lee Giles, and Frans Coetzee, 2002" | |
32 | * @see "http://www.neci.nec.com/~lawrence/papers/web-computer02/web-computer02.pdf" | |
33 | */ | |
34 | public class ExactFlowCommunity { | |
35 | private int mCohesionThreshold; | |
36 | ||
37 | /** | |
38 | * Constructs and initializes the algorithm | |
39 | * @param cohesionThreshold a heuristic value that determines the | |
40 | * level of cohesion for the community to be extracted | |
41 | */ | |
42 | 2 | public ExactFlowCommunity(int cohesionThreshold) { |
43 | 2 | mCohesionThreshold = cohesionThreshold; |
44 | 2 | } |
45 | ||
46 | /** | |
47 | * Extracts the community according to the cohesion threshold | |
48 | * @param graph the original graph | |
49 | * @param rootSet the set of nodes used to see the community | |
50 | * @return a set of nodes representative of the community used to seed the algorithm | |
51 | */ | |
52 | public Set extract(DirectedGraph graph, Set rootSet) { | |
53 | 4 | DirectedGraph flowGraph = (DirectedGraph) graph.copy(); |
54 | 4 | Vertex source = flowGraph.addVertex(new SparseVertex()); |
55 | 4 | Vertex sink = flowGraph.addVertex(new SparseVertex()); |
56 | ||
57 | 4 | initializeFlowGraph(flowGraph,source, sink,rootSet); |
58 | 4 | EdmondsKarpMaxFlow maxFlowSolver = new EdmondsKarpMaxFlow(flowGraph,source,sink,"CAPACITY","FLOW"); |
59 | 4 | maxFlowSolver.evaluate(); |
60 | 4 | Set communityVertices = new HashSet(); |
61 | 4 | Set sourceNodes = maxFlowSolver.getNodesInSourcePartition(); |
62 | 4 | for (Iterator vIt = sourceNodes.iterator();vIt.hasNext();) { |
63 | 22 | Vertex v = (Vertex) vIt.next(); |
64 | 22 | if (v.getEqualVertex(flowGraph) != source) { |
65 | 18 | communityVertices.add(v.getEqualVertex(graph)); |
66 | } | |
67 | } | |
68 | ||
69 | 4 | return communityVertices; |
70 | } | |
71 | ||
72 | /** | |
73 | * Implements the "ApproximateFlowCommunity" algorithm. Repeatedly | |
74 | * finds the community at low distances from the starting set, and | |
75 | * grows outward. UNDERTESTED. | |
76 | * @param graph the original graph | |
77 | * @param rootSet the set of nodes used to see the community | |
78 | * @return a set of nodes representative of the community used to seed the algorithm | |
79 | */ | |
80 | public static Set extract(DirectedGraph graph, Set rootSet, int numIterations) { | |
81 | 0 | Set members = new HashSet(rootSet); |
82 | 0 | Set newMembers = null; |
83 | 0 | int numPreviousMembers = members.size(); |
84 | 0 | int numCurrentMembers = 0; |
85 | ||
86 | 0 | for (int i=0;i<numIterations;i++) { |
87 | 0 | ExactFlowCommunity ecf = new ExactFlowCommunity(members.size()); |
88 | 0 | newMembers = ecf.extract(graph,members); |
89 | 0 | numCurrentMembers = newMembers.size(); |
90 | 0 | if (numPreviousMembers == numCurrentMembers) { |
91 | 0 | break; |
92 | } | |
93 | 0 | numPreviousMembers = numCurrentMembers; |
94 | 0 | System.out.println(members.size()); |
95 | 0 | DoubleArrayList inDegrees = DegreeDistributions.getIndegreeValues(newMembers); |
96 | 0 | int maxIndegree = (int) Descriptive.max(inDegrees); |
97 | 0 | DoubleArrayList outDegrees = DegreeDistributions.getOutdegreeValues(newMembers); |
98 | 0 | int maxOutdegree = (int) Descriptive.max(outDegrees); |
99 | ||
100 | 0 | for (Iterator vIt = newMembers.iterator(); vIt.hasNext();) { |
101 | 0 | Vertex v = (Vertex) vIt.next(); |
102 | 0 | if (members.contains(v)) { |
103 | 0 | continue; |
104 | } | |
105 | 0 | if (v.inDegree() == maxIndegree) { |
106 | 0 | members.add(v); |
107 | 0 | } else if (v.outDegree() == maxOutdegree) { |
108 | 0 | members.add(v); |
109 | } | |
110 | } | |
111 | } | |
112 | ||
113 | 0 | return newMembers; |
114 | ||
115 | } | |
116 | ||
117 | /** | |
118 | * Initialize the flow graph | |
119 | * @param flowGraph the flow graph | |
120 | * @param source the source node | |
121 | * @param sink the sink node | |
122 | * @param rootSet the set of nodes used to seed the community | |
123 | */ | |
124 | protected void initializeFlowGraph(DirectedGraph flowGraph,Vertex source, Vertex sink,Set rootSet) { | |
125 | ||
126 | 4 | NumericDecorator capacityDecorator = new NumericDecorator("CAPACITY",UserData.SHARED); |
127 | ||
128 | 4 | List edgesList = new ArrayList(); |
129 | 4 | edgesList.addAll(flowGraph.getEdges()); |
130 | ||
131 | 76 | for (int idx = 0; idx < edgesList.size(); idx++) { |
132 | 72 | DirectedEdge currentEdge = (DirectedEdge) edgesList.get(idx); |
133 | 72 | capacityDecorator.setValue(new MutableInteger(mCohesionThreshold),currentEdge); |
134 | ||
135 | // finds edges that aren't reciprocated | |
136 | // that is, this is an edge from (A to B). This looks for the edge that runs from B to A. | |
137 | 72 | Edge otherEdge = currentEdge.getDest().findEdge(currentEdge.getSource()); |
138 | 72 | if (otherEdge == null) { |
139 | 24 | otherEdge = GraphUtils.addEdge(flowGraph,currentEdge.getDest(),currentEdge.getSource()); |
140 | 24 | capacityDecorator.setValue(new MutableInteger(mCohesionThreshold),otherEdge); |
141 | } | |
142 | } | |
143 | ||
144 | 4 | for (Iterator vIt = flowGraph.getVertices().iterator(); vIt.hasNext();) { |
145 | 48 | Vertex currentVertex = (Vertex) vIt.next(); |
146 | 48 | if (currentVertex != sink && !rootSet.contains(currentVertex)) { |
147 | 36 | Edge newEdge = GraphUtils.addEdge(flowGraph,currentVertex,sink); |
148 | 36 | capacityDecorator.setValue(new MutableInteger(1),newEdge); |
149 | } | |
150 | } | |
151 | ||
152 | 4 | for (Iterator rootIt = rootSet.iterator(); rootIt.hasNext();) { |
153 | 8 | Vertex currentRoot = (Vertex) rootIt.next(); |
154 | 8 | currentRoot = (Vertex) currentRoot.getEqualVertex(flowGraph); |
155 | 8 | Edge e= GraphUtils.addEdge(flowGraph,source,currentRoot); |
156 | 8 | capacityDecorator.setValue(new MutableInteger(Integer.MAX_VALUE),e); |
157 | } | |
158 | 4 | } |
159 | } |
this report was generated by version 1.0.5 of jcoverage. |
copyright © 2003, jcoverage ltd. all rights reserved. |