def get_last_tid(self):
        try:
            spec = {'tid': {'$gt': 0}}
            sort = [('tid', -1)]
            row = self.db.docs.find_one(spec, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        if row:
            return row['tid']
        return 0
def __normalize_probabilities(self):
        for index_point in range(len(self.__data)):
            probability = 0.0
            for index_cluster in range(len(self.__clusters)):
                probability += self.__rc[index_cluster][index_point]