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64 lines
2.2 KiB
64 lines
2.2 KiB
4 months ago
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import degree from './degree';
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import { getNeighbors } from "./util";
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/**
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* PageRank https://en.wikipedia.org/wiki/PageRank
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* refer: https://github.com/anvaka/ngraph.pagerank
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* @param graph
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* @param epsilon 判断是否收敛的精度值，默认 0.000001
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* @param linkProb 阻尼系数（dumping factor），指任意时刻，用户访问到某节点后继续访问该节点链接的下一个节点的概率，经验值 0.85
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*/
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var pageRank = function pageRank(graphData, epsilon, linkProb) {
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if (typeof epsilon !== 'number') epsilon = 0.000001;
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if (typeof linkProb !== 'number') linkProb = 0.85;
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var distance = 1;
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var leakedRank = 0;
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var maxIterations = 1000;
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var _a = graphData.nodes,
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nodes = _a === void 0 ? [] : _a,
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_b = graphData.edges,
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edges = _b === void 0 ? [] : _b;
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var nodesCount = nodes.length;
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var currentRank;
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var curRanks = {};
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var prevRanks = {};
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// Initialize pageranks 初始化
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for (var j = 0; j < nodesCount; ++j) {
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var node = nodes[j];
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var nodeId = node.id;
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curRanks[nodeId] = 1 / nodesCount;
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prevRanks[nodeId] = 1 / nodesCount;
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}
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var nodeDegree = degree(graphData);
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while (maxIterations > 0 && distance > epsilon) {
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leakedRank = 0;
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for (var j = 0; j < nodesCount; ++j) {
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var node = nodes[j];
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var nodeId = node.id;
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currentRank = 0;
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if (nodeDegree[node.id].inDegree === 0) {
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curRanks[nodeId] = 0;
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} else {
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var neighbors = getNeighbors(nodeId, edges, 'source');
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for (var i = 0; i < neighbors.length; ++i) {
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var neighbor = neighbors[i];
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var outDegree = nodeDegree[neighbor].outDegree;
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if (outDegree > 0) currentRank += prevRanks[neighbor] / outDegree;
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}
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curRanks[nodeId] = linkProb * currentRank;
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leakedRank += curRanks[nodeId];
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}
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}
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leakedRank = (1 - leakedRank) / nodesCount;
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distance = 0;
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for (var j = 0; j < nodesCount; ++j) {
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var node = nodes[j];
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var nodeId = node.id;
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currentRank = curRanks[nodeId] + leakedRank;
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distance += Math.abs(currentRank - prevRanks[nodeId]);
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prevRanks[nodeId] = currentRank;
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}
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maxIterations -= 1;
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}
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return prevRanks;
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};
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export default pageRank;
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