def getall(self):
        try:
            spec = {'data': {'$exists': 1}}
            fields = {'_id': 0}
            sort = [('tid', 1)]
            cur = self.db.docs.find(spec, fields, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        return [Document(**row) for row in cur]
def __initialize_kmeans(self):
        initial_centers = kmeans_plusplus_initializer(self.__sample, self.__amount).initialize()
        kmeans_instance = kmeans(self.__sample, initial_centers, ccore = True)
        kmeans_instance.process()