Does the simple thing - if any group is empty, but needs to have at
        least one member, assign the data point with highest probability of
        membership

def _fill_empty_groups_old(self, probs, assignment):
        """ Does the simple thing - if any group is empty, but needs to have at
        least one member, assign the data point with highest probability of
        membership """
        new_assignment = np.array(assignment.tolist())
        for k in range(self.numgrp):
            if np.count_nonzero(assignment==k) == 0:
                logger.info('Group {} became empty'.format(k))
                best = np.where(probs[:,k]==probs[:,k].max())[0][0]
                new_assignment[best] = k
                new_assignment = self._fill_empty_groups(probs, new_assignment)
        return new_assignment