def __init__(self):
		'''创建表'''
		self.conn = sqlite3.connect("./items.db")
		if VERBOSE:
			print 'Database connection OPEN.'
		# Domain 表
		self.conn.execute(CTABLE_DOMAIN)
		# Website 表
		self.conn.execute(CTABLE_WEBSITE)
		# Rule 表 
		self.conn.execute(CTABLE_RULESETS)

		self.conn.commit()
		if VERBOSE:
			cur = self.conn.cursor()
			print 'Tables:',cur.execute("SELECT name FROM sqlite_master WHERE type = 'table'").fetchall()
def __calculate_initial_covariances(self, initial_clusters):
        covariances = []
        for initial_cluster in initial_clusters:
            if len(initial_cluster) > 1:
                cluster_sample = [self.__sample[index_point] for index_point in initial_cluster]
                covariances.append(numpy.cov(cluster_sample, rowvar=False))
            else:
                dimension = len(self.__sample[0])
                covariances.append(numpy.zeros((dimension, dimension)) + random.random() / 10.0)