code: void init() {
      numnegative = new int[numSamples() + 1];
      numpositive = new int[numSamples() + 1];
      numnegative[0] = 0;
      numpositive[0] = 0;
      int num = numSamples();
      for (int i = 1; i <= num; i++) {
        numnegative[i] = numnegative[i - 1] + (classes[i - 1] == 0 ? 1 : 0);
      }
      for (int i = 1; i <= num; i++) {
        numpositive[i] = numpositive[i - 1] + (classes[num - i] == 0 ? 0 : 1);
      }
      System.err.println("total positive " + numpositive[num] + " total negative " + numnegative[num] + " total " + num);
      for (int i = 1; i < numpositive.length; i++) {
        //System.out.println(i + " positive " + numpositive[i] + " negative " + numnegative[i] + " classes " + classes[i - 1] + " " + classes[num - i]);
      }
    }
docs: initialize the numpositive and the numnegative arrays