def ordered_members_map(self):
        """
        Mask to group the persons by entity
        This function only caches the map value, to see what the map is used for, see value_nth_person method.
        """
        if self._ordered_members_map is None:
            return np.argsort(self.members_entity_id)
        return self._ordered_members_map
Mask to group the persons by entity
        This function only caches the map value, to see what the map is used for, see value_nth_person method.