docs: private double avgDistance(double[] centroid, DBIDs objectIDs, Relation<V> database, int dimension) {
      Mean avg = new Mean();
      for(DBIDIter iter = objectIDs.iter(); iter.valid(); iter.advance()) {
        V o = database.get(iter);
        avg.put(Math.abs(centroid[dimension] - o.doubleValue(dimension)));
      }
      return avg.getMean();
    }