[Java]SimRank

有关SimRank请参看文章http://www.cnblogs.com/youwang/archive/2010/02/06/1665105.html，或者去看相关论文。下面是Java代码实现，用到的是webgraph库。

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package cn.edu.dlut.wisdom;
 
import it.unimi.dsi.fastutil.ints.*;
import it.unimi.dsi.webgraph.*;
 
/**
 *
 * @author You Wang
 */
public class SimRank {
 
    private ImmutableGraph graph;
    private ImmutableGraph igraph;
    private double dampening = 0.85;
    private Int2ObjectArrayMap<Int2DoubleArrayMap> scores;
 
    public double getDampening() {
        return dampening;
    }
 
    public void setDampening(double dampening) {
        this.dampening = dampening;
    }
 
    public SimRank(ImmutableGraph graph) {
        this.graph = graph;
        this.igraph = Transform.transpose(graph);
    }
 
    public SimRank(ImmutableGraph graph, ImmutableGraph igraph) {
        this.graph = graph;
        this.igraph = igraph;
    }
 
    public void computeSimRank() {
        int n = graph.numNodes();
    int iter = ((int) Math.abs(Math.log((double) n) / Math.log((double) 10))) + 1;
        computeSimRank(iter);
    }
 
    public Int2DoubleArrayMap getSimRank(int i) {
        return scores.get(i);
    }
 
    public Int2ObjectArrayMap getSimRank() {
        return scores;
    }
 
    public double getSimRank(int i, int j) {
        return scores.get(i).get(j);
    }
 
    public void computeSimRank(int iter) {
        // 初始化
        int numNodes = graph.numNodes();
        this.scores = new Int2ObjectArrayMap<Int2DoubleArrayMap>(numNodes);
        for (int i = 0; i < numNodes; i++) {
            Int2DoubleArrayMap aux = new Int2DoubleArrayMap(numNodes);
            for (int j = 0; j < numNodes; j++) {
                if (i == j)
                    aux.put(j, 1);
                else
                    aux.put(j, 0);
            }
            scores.put(i, aux);
        }
 
        // 迭代计算
        while(iter-- > 0)
        {
            for(int i = 0; i < numNodes; i++) {
                int numInNeighborsi = igraph.outdegree(i);
                if(numInNeighborsi == 0)
                    continue;
                int[] inNeighborsi = igraph.successorArray(i);
                Int2DoubleArrayMap rimap = scores.get(i);
                for(int j = 0; j < numNodes; j++) {
                    int numInNeighborsj = igraph.outdegree(j);
                    if(numInNeighborsj == 0)
                        continue;
                    int[] inNeighborsj = igraph.successorArray(j);
                    double rab = 0;
                    for(int a : inNeighborsi) {
                        Int2DoubleArrayMap aux = scores.get(a);
                        for(int b : inNeighborsj) {
                            rab += aux.get(b);
                        }
                    }
                    rab *= dampening / (numInNeighborsi * numInNeighborsj);
                    rimap.put(j, rab);
                }
            }
        }
    }
}