public void generateNominalValues(List<Word> data_points) {
    if (!isNominal()) {
      setNominal();
    }
    for (Region r : data_points) {
      if (r.getAttribute(name) == null) {
        System.err.println("Region " + r + " has no attribute: " + name);
        AuToBIUtils.debug("Region " + r + " has no attribute: " + name);
      } else if (r.getAttribute(name) instanceof String) {
        addNominalValue((String) r.getAttribute(name));
      } else if (r.getAttribute(name) instanceof Number) {
        addNominalValue(r.getAttribute(name).toString());
      }
    }
  }