code: public void centerInstances(Instances centers, int[] assignments, double pc)
        throws Exception {
  
      int[] centList = new int[centers.numInstances()];
      for (int i = 0; i < centers.numInstances(); i++)
        centList[i] = i;
  
      determineAssignments(m_Root, centers, centList, assignments, pc);
    }
docs: Assigns instances to centers using KDTree.
  
  @param centers	the current centers
  @param assignments	the centerindex for each instance
  @param pc		the threshold value for pruning.
  @throws Exception If there is some problem
  assigning instances to centers.