@Override
    public int compareTo(RepairNode o) {
      double u1 = Math.abs(this.u - center);
      double u2 = Math.abs(o.u - center);
      if (u1 > u2) {
        return -1;
      } else if (u1 == u2) {
        return 0;
      } else {
        return 1;
      }
    }
modify values of repaired points, to make the difference of its speed variation and center is
1 sigma.
library-udf/src/main/java/org/apache/iotdb/library/drepair/util/LsGreedy.java