docs: public static ProjectedCentroid make(long[] dims, Relation<? extends NumberVector> relation) {
      ProjectedCentroid c = new ProjectedCentroid(dims, RelationUtil.dimensionality(relation));
      for(DBIDIter iditer = relation.iterDBIDs(); iditer.valid(); iditer.advance()) {
        c.put(relation.get(iditer));
      }
      return c;
    }