init=tf.global_variables_initializer()
with tf.Session() as sess
sess.run(init)
如果欠缺这一步会出现错误：
FailedPreconditionError Traceback (most recent call last)
~/anaconda3/lib/python3.6/site-packages/tensorflow/python/client/session.py in _do_call(self, fn, *args) 1355 try: -> 1356 return fn(*args) 1357 except errors.OpError as e: ~/anaconda3/lib/python3.6/site-packages/tensorflow/python/client/session.py in _run_fn(feed_dict, fetch_list, target_list, options, run_metadata) 1340 return self._call_tf_sessionrun( -> 1341 options, feed_dict, fetch_list, target_list, run_metadata) 1342 ~/anaconda3/lib/python3.6/site-packages/tensorflow/python/client/session.py in _call_tf_sessionrun(self, options, feed_dict, fetch_list, target_list, run_metadata) 1428 self._session, options, feed_dict, fetch_list, target_list, -> 1429 run_metadata) 1430