docs: public static List<DataPoint> getDatapointsFromCluster(int c, int[] assignments, DataSet dataSet, int[] indexFrom)
      {
          List<DataPoint> list = new ArrayList<>();
          int pos = 0;
          for(int i = 0; i < dataSet.size(); i++)
              if(assignments[i] == c)
              {
                  list.add(dataSet.getDataPoint(i));
                  if(indexFrom != null)
                      indexFrom[pos++] = i;
              }
          return list;
      }