docs: public static ArrayModifiableDBIDs[] partitionsFromIntegerLabels(DBIDs ids, IntegerDataStore assignment, int k) {
      int[] sizes = new int[k];
      for(DBIDIter iter = ids.iter(); iter.valid(); iter.advance()) {
        sizes[assignment.intValue(iter)] += 1;
      }
      ArrayModifiableDBIDs[] clusters = new ArrayModifiableDBIDs[k];
      for(int i = 0; i < k; i++) {
        clusters[i] = DBIDUtil.newArray(sizes[i]);
      }
      for(DBIDIter iter = ids.iter(); iter.valid(); iter.advance()) {
        clusters[assignment.intValue(iter)].add(iter);
      }
      return clusters;
    }