code: @Override
      public int predict(T x) {
          List<Neighbor<T,T>> neighbors = new ArrayList<>();
          nns.range(x, radius, neighbors);
          
          if (neighbors.size() < minPts) {
              return OUTLIER;
          }
          
          int[] label = new int[k + 1];
          for (Neighbor<T,T> neighbor : neighbors) {
              int yi = y[neighbor.index];
              if (yi == OUTLIER) yi = k;
              label[yi]++;
          }
          
          int c = Math.whichMax(label);
          if (c == k) c = OUTLIER;
          return c;
      }
docs: Cluster a new instance.
  @param x a new instance.
  @return the cluster label. Note that it may be {@link #OUTLIER}.