TensorFlow：変数を計算するセッションを入力しますか？ FailedPreconditionError：私は以下の変数Wの値を見つけるためにTensorFlowセッションを実行しようとしています

Question

weight_2初期化されていない値を使用しようとするが、私のコードです：

：

W = tf.Variable(rng.randn(), name="weight") 
init = tf.initialize_all_variables() 

print(W.dtype) 
print(W.initial_value) 
print(W.value) 

sess = tf.Session() 
sess.run(W) 

それから私は、次の出力に&エラーを得ました

<dtype: 'float32_ref'> 
Tensor("weight_2/initial_value:0", shape=(), dtype=float32) 
<bound method Variable.value of <tensorflow.python.ops.variables.Variable object at 0x7f031f36a470>> 
--------------------------------------------------------------------------- 
FailedPreconditionError     Traceback (most recent call last) 
/usr/local/lib/python3.4/dist-packages/tensorflow/python/client/session.py in _do_call(self, fn, *args) 
    971  try: 
--> 972  return fn(*args) 
    973  except errors.OpError as e: 

/usr/local/lib/python3.4/dist-packages/tensorflow/python/client/session.py in _run_fn(session, feed_dict, fetch_list, target_list, options, run_metadata) 
    953         feed_dict, fetch_list, target_list, 
--> 954         status, run_metadata) 
    955 

/usr/lib/python3.4/contextlib.py in __exit__(self, type, value, traceback) 
    65    try: 
---> 66     next(self.gen) 
    67    except StopIteration: 

/usr/local/lib/python3.4/dist-packages/tensorflow/python/framework/errors.py in raise_exception_on_not_ok_status() 
    462   compat.as_text(pywrap_tensorflow.TF_Message(status)), 
--> 463   pywrap_tensorflow.TF_GetCode(status)) 
    464 finally: 

FailedPreconditionError: Attempting to use uninitialized value weight_2 
    [[Node: _send_weight_2_0 = _Send[T=DT_FLOAT, client_terminated=true, recv_device="/job:localhost/replica:0/task:0/cpu:0", send_device="/job:localhost/replica:0/task:0/cpu:0", send_device_incarnation=-1169476299400319384, tensor_name="weight_2:0", _device="/job:localhost/replica:0/task:0/cpu:0"](weight_2)]] 

During handling of the above exception, another exception occurred: 

FailedPreconditionError     Traceback (most recent call last) 
<ipython-input-35-892407d423e3> in <module>() 
     7 
     8 sess = tf.Session() 
----> 9 sess.run(W) 

/usr/local/lib/python3.4/dist-packages/tensorflow/python/client/session.py in run(self, fetches, feed_dict, options, run_metadata) 
    715  try: 
    716  result = self._run(None, fetches, feed_dict, options_ptr, 
--> 717       run_metadata_ptr) 
    718  if run_metadata: 
    719   proto_data = tf_session.TF_GetBuffer(run_metadata_ptr) 

/usr/local/lib/python3.4/dist-packages/tensorflow/python/client/session.py in _run(self, handle, fetches, feed_dict, options, run_metadata) 
    913  if final_fetches or final_targets: 
    914  results = self._do_run(handle, final_targets, final_fetches, 
--> 915        feed_dict_string, options, run_metadata) 
    916  else: 
    917  results = [] 

/usr/local/lib/python3.4/dist-packages/tensorflow/python/client/session.py in _do_run(self, handle, target_list, fetch_list, feed_dict, options, run_metadata) 
    963  if handle is None: 
    964  return self._do_call(_run_fn, self._session, feed_dict, fetch_list, 
--> 965       target_list, options, run_metadata) 
    966  else: 
    967  return self._do_call(_prun_fn, self._session, handle, feed_dict, 

/usr/local/lib/python3.4/dist-packages/tensorflow/python/client/session.py in _do_call(self, fn, *args) 
    983   except KeyError: 
    984   pass 
--> 985  raise type(e)(node_def, op, message) 
    986 
    987 def _extend_graph(self): 

FailedPreconditionError: Attempting to use uninitialized value weight_2 
    [[Node: _send_weight_2_0 = _Send[T=DT_FLOAT, client_terminated=true, recv_device="/job:localhost/replica:0/task:0/cpu:0", send_device="/job:localhost/replica:0/task:0/cpu:0", send_device_incarnation=-1169476299400319384, tensor_name="weight_2:0", _device="/job:localhost/replica:0/task:0/cpu:0"](weight_2)]] 

私は、セッションを実行するにはWの式が必要だと推測していますが、何が必要なのか正確には分かっていません...セッションが値を計算できるように正確に何が提供される必要がありますか変数の？ありがとう！

Answer 1

機能名initialize_all_variablesは少し誤解を招く（0.12で変更されています）。実行する必要があるオペレーションを返します。 Wはsess.run(init)に電話するまで初期化されません。

W.initial_valueはそれが私はドキュメント（強調鉱山）で読んだから、で初期化されますという値を示しています

tf.Variable.initial_value

Returns the Tensor used as the initial value for the variable.

Note that this is different from initialized_value() which runs the op that initializes the variable before returning its value. This method returns the tensor that is used by the op that initializes the variable.