HITS.java

package xyz.anduo.crawler;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

/**
 * HTIS HTIS算法
 * 
 * @author anduo
 * 
 */
public class HITS {
  /** 存储web图的数据结构 */
  private WebGraphMemory graph;

  /** 包含每个网页的评分 */
  private Map<Integer, Double> hubScores; // <id,value>

  /** 包含每个网页的Authority */
  private Map<Integer, Double> authorityScores;// <id,value>

  /**
   * 构造函数
   */
  public HITS(WebGraphMemory graph) {
    this.graph = graph;
    this.hubScores = new HashMap<Integer, Double>();
    this.authorityScores = new HashMap<Integer, Double>();
    int numLinks = graph.numNodes();
    for (int i = 1; i <= numLinks; i++) {
      hubScores.put(new Integer(i), new Double(1));
      authorityScores.put(new Integer(i), new Double(1));
    }
    computeHITS();
  }

  /**
   * 计算网页的 Hub 和 Authority scores
   */
  public void computeHITS() {
    computeHITS(25);
  }

  /**
   * 计算网页的 Hub 和 Authority scores
   * 
   */
  public void computeHITS(int numIterations) {

    while (numIterations-- > 0) {
      for (int i = 1; i <= graph.numNodes(); i++) {
        Map<Integer, Double> inlinks = graph.inLinks(new Integer(i));
        Map<Integer, Double> outlinks = graph.outLinks(new Integer(i));
        double authorityScore = 0;
        double hubScore = 0;
        for (Integer id : inlinks.keySet()) {
          authorityScore += (hubScores.get(id)).doubleValue();
        }

        for (Integer id : outlinks.keySet()) {
          hubScore += (authorityScores.get(id)).doubleValue();
        }

        authorityScores.put(new Integer(i), new Double(authorityScore));
        hubScores.put(new Integer(i), new Double(hubScore));
      }
      normalize(authorityScores);
      normalize(hubScores);
    }
  }

  public void computeWeightedHITS(int numIterations) {
    while (numIterations-- > 0) {
      for (int i = 1; i <= graph.numNodes(); i++) {
        Map<Integer, Double> inlinks = graph.inLinks(new Integer(i));
        Map<Integer, Double> outlinks = graph.outLinks(new Integer(i));
        double authorityScore = 0;
        double hubScore = 0;
        for (Map.Entry<Integer, Double> in : inlinks.entrySet()) {
          authorityScore += (hubScores.get(in.getKey())).doubleValue() * in.getValue();
        }

        for (Map.Entry<Integer, Double> out : outlinks.entrySet()) {
          hubScore += (authorityScores.get(out.getKey())).doubleValue() * out.getValue();
        }

        authorityScores.put(new Integer(i), new Double(authorityScore));
        hubScores.put(new Integer(i), new Double(hubScore));
      }
      normalize(authorityScores);
      normalize(hubScores);
    }
  }

  /**
   * Normalize the set
   */
  private void normalize(Map<Integer, Double> scoreSet) {
    Iterator<Integer> iter = scoreSet.keySet().iterator();
    double summation = 0.0;
    while (iter.hasNext())
      summation += ((scoreSet.get((Integer) (iter.next())))).doubleValue();

    iter = scoreSet.keySet().iterator();
    while (iter.hasNext()) {
      Integer id = iter.next();
      scoreSet.put(id, (scoreSet.get(id)).doubleValue() / summation);
    }
  }

  /**
   * 返回与给定链接关联的Hub score
   */
  public Double hubScore(String link) {
    return hubScore(graph.URLToIdentifyer(link));
  }

  /**
   * 返回与给定链接关联的Hub score
   */
  private Double hubScore(Integer id) {
    return (Double) (hubScores.get(id));
  }

  /**
   * 初始化与给定链接关联的Hub score
   */
  public void initializeHubScore(String link, double value) {
    Integer id = graph.URLToIdentifyer(link);
    if (id != null)
      hubScores.put(id, new Double(value));
  }

  /**
   * 初始化与给定链接关联的Hub score
   */
  public void initializeHubScore(Integer id, double value) {
    if (id != null)
      hubScores.put(id, new Double(value));
  }

  /**
   * 返回与给定链接关联的 Authority score
   */
  public Double authorityScore(String link) {
    return authorityScore(graph.URLToIdentifyer(link));
  }

  /**
   * 返回与给定链接关联的 Authority score
   */
  private Double authorityScore(Integer id) {
    return (Double) (authorityScores.get(id));
  }

  /**
   * 初始化与给定链接关联的 Authority score
   */
  public void initializeAuthorityScore(String link, double value) {
    Integer id = graph.URLToIdentifyer(link);
    if (id != null)
      authorityScores.put(id, new Double(value));
  }

  /**
   * 初始化与给定链接关联的 Authority score
   */
  public void initializeAuthorityScore(Integer id, double value) {
    if (id != null)
      authorityScores.put(id, new Double(value));
  }
}