java 实现PageRank算法

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java实现PageRank算法，直接上源码
package pagerank;  import java.io.BufferedReader;  import java.io.BufferedWriter;  import java.io.File;  import java.io.FileReader;  import java.io.FileWriter;  import java.util.Hashtable;  public class PageRank {      public static void main(String[] args) throws Exception {          String[] linesarr;          Hashtable<String, Integer> docIDandNum = new Hashtable<String, Integer>();          int total = 0;          int father, son;          int outdegree = 0;          // 读取文件，得到docid，计算链接总数total，outdegree在迭代的时候计算          File linkfile = new File("E:/larbin/linkmaptest.txt");          BufferedReader linkinput = new BufferedReader(new FileReader(linkfile));          String line = linkinput.readLine();          while (line != null) {              ++total;              linesarr = line.split(" ");              if (linesarr.length > 0) {                  // outdegree = linesarr.length - 1;                  // for(int j = 1; j <= linesarr.length - 1; ++j) {                  // if(linesarr[j].equals(linesarr[0]))                  // outdegree--;                  // }                  if (linesarr[0] != null) {                      docIDandNum.put(linesarr[0], total);                      // System.out.println("链接" + linesarr[0] + "的出度为" + outdegree);                  }              }              linesarr = null;              line = linkinput.readLine();          }          linkinput.close();          // System.out.println("链接总数为：" + total);          if (total > 0) {              // pageRank[]存放PR值              float[] pageRank = new float[total + 1];               // 链入页面的计算总和              float[] prTmp = new float[total + 1];                // 设置pageRank[]初始值为1.0f              for (int i = 1; i <= total; ++i) {                  pageRank[i] = 1.0f;                  prTmp[i] = 0.0f;              }               // 当前页面的PR值              float fatherRank = 1f;              // 阻尼系数d或称为alpha              float alpha = 0.85f;               // 进行10次迭代              for (int iterator = 0; iterator < 10; iterator++) {                   long startTime = System.currentTimeMillis();                  linkinput = new BufferedReader(new FileReader(linkfile));                  line = linkinput.readLine();                  // 读出docid和outdegree和sons                  while (line != null) {                       linesarr = line.split(" ");                      if (linesarr.length > 0) {                          outdegree = linesarr.length - 1;                          for (int j = 1; j <= linesarr.length - 1; ++j) {                               // 指向自身的链接无效，不计算在内                              if (linesarr[j].equals(linesarr[0]))                                  outdegree--;                          }                      }                      if (outdegree > 0) {                          father = (int) docIDandNum.get(linesarr[0]);                           // 对应公式中的pr(Ti)/c(Ti),Ti为指向father的页面                          fatherRank = pageRank[father] / outdegree;                          for (int k = 1; k <= linesarr.length - 1; ++k) {                              if (linesarr[k].equals(linesarr[0])) {                                  continue;                              }                              son = docIDandNum.get(linesarr[k]);                              if (total >= son && son >= 0) {                                  prTmp[son] += fatherRank;                              }                          }                      }                      linesarr = null;                      line = linkinput.readLine();                  }                  // 准备下次迭代的初始值                  for (int i = 1; i <= total; ++i)     {                      // PR公式1                      // prTmp[i] = 0.15f + alpha * prTmp[i];                      // PR公式2                      prTmp[i] = 0.15f / total + alpha * prTmp[i];                       // 每次迭代后的真正pr值                      pageRank[i] = prTmp[i];                       prTmp[i] = 0.0f;                  }                  // 打印出每次迭代值，此操作耗费时间和内存                  // for (int i = 1; i <= total; ++i)                  // System.out.print(pageRank[i] + " \t ");                  // System.out.println(" ");                  linkinput.close();                  long endTime = System.currentTimeMillis();                  System.out.println("第" + iterator + "次迭代耗时" + (endTime - startTime) + "ms");              }              //最终PR值输出至文件              BufferedWriter newlink = new BufferedWriter(new FileWriter(                      new File("E:/larbin/pageranktest.txt")));              for (int i = 1; i <= total; ++i) {                  // System.out.println(docIDandNum.toString());                  newlink.write(String.valueOf(pageRank[i]));                  newlink.newLine();              }              newlink.flush();              newlink.close();              pageRank = null;              prTmp = null;          }      }  }
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