private String mergeKernels()

in samoa-api/src/main/java/org/apache/samoa/streams/clustering/RandomRBFGeneratorEvents.java [750:807]
45 lines of code
18 McCabe index (conditional complexity)

  private String mergeKernels(int steps) {
    if (numActiveKernels > 1 && ((mergeClusterA == null && mergeClusterB == null))) {

      // choose clusters to merge
      double diseredDist = steps / speedOption.getValue() * maxDistanceMoveThresholdByStep;
      double minDist = Double.MAX_VALUE;
      // System.out.println("DisredDist:"+(2*diseredDist));
      for (int i = 0; i < kernels.size(); i++) {
        for (int j = 0; j < i; j++) {
          if (kernels.get(i).kill == -1 && kernels.get(j).kill == -1) {
            double kernelDist = kernels.get(i).generator.getCenterDistance(kernels.get(j).generator);
            double d = kernelDist - 2 * diseredDist;
            // System.out.println("Dist:"+i+" / "+j+" "+d);
            if (Math.abs(d) < minDist &&
                (minDist != Double.MAX_VALUE || d > 0 || Math.abs(d) < 0.001)) {
              minDist = Math.abs(d);
              mergeClusterA = kernels.get(i);
              mergeClusterB = kernels.get(j);
            }
          }
        }
      }

      if (mergeClusterA != null && mergeClusterB != null) {
        double[] merge_point = mergeClusterA.generator.getCenter();
        double[] v = mergeClusterA.generator.getDistanceVector(mergeClusterB.generator);
        for (int i = 0; i < v.length; i++) {
          merge_point[i] = merge_point[i] + v[i] * 0.5;
        }

        mergeClusterA.merging = true;
        mergeClusterB.merging = true;
        mergeClusterA.setDesitnation(merge_point);
        mergeClusterB.setDesitnation(merge_point);

        if (debug) {
          System.out.println("Center1" + Arrays.toString(mergeClusterA.generator.getCenter()));
          System.out.println("Center2" + Arrays.toString(mergeClusterB.generator.getCenter()));
          System.out.println("Vector" + Arrays.toString(v));

          System.out.println("Try to merge cluster " + mergeClusterA.generator.getId() +
              " into " + mergeClusterB.generator.getId() +
              " at " + Arrays.toString(merge_point) +
              " time " + numGeneratedInstances);
        }
        return "Init merge";
      }
    }

    if (mergeClusterA != null && mergeClusterB != null) {

      // movekernels will move the kernels close to each other,
      // we just need to check and merge here if they are close enough
      return mergeClusterA.tryMerging(mergeClusterB);
    }

    return "";
  }