docs: public static int globalCentroid(Centroid overallCentroid, Relation<? extends NumberVector> rel, List<? extends Cluster<?>> clusters, NumberVector[] centroids, NoiseHandling noiseOption) {
      int clustercount = 0;
      Iterator<? extends Cluster<?>> ci = clusters.iterator();
      for(int i = 0; ci.hasNext(); i++) {
        Cluster<?> cluster = ci.next();
        if(cluster.size() <= 1 || cluster.isNoise()) {
          switch(noiseOption){
          case IGNORE_NOISE:
            continue; // Ignore completely
          case TREAT_NOISE_AS_SINGLETONS:
            clustercount += cluster.size();
            // Update global centroid:
            for(DBIDIter it = cluster.getIDs().iter(); it.valid(); it.advance()) {
              overallCentroid.put(rel.get(it));
            }
            continue; // With NEXT cluster.
          case MERGE_NOISE:
            break; // Treat as cluster below:
          }
        }
        // Update centroid:
        assert (centroids[i] != null);
        overallCentroid.put(centroids[i], cluster.size());
        ++clustercount;
      }
      return clustercount;
    }