テンソルフローwhile_loop：ValueError：値がサポートされていません

Question

グラフにテンソルオブジェクトをスライスして使用しようとしています。コードは以下の通りである：

self.batchSizeは tf.int32の placeholderある

 utt_inputs = [] 
     idx = tf.zeros(shape=(), dtype=tf.int32) 
     def add_inputs(idx): 
      utt_input = tf.slice(last_outputs, begin=[idx, 0], size=[self.args.uttWindowSize, self.args.wordUnits]) 
      utt_inputs.append(utt_input) 

     def my_cond(idx): 
      idx = tf.add(idx, 1) 
      return tf.less(idx, self.batchSize) 

     tf.while_loop(cond=my_cond, body=add_inputs, loop_vars=[idx]) 

。 Last_outputsは2-dテンソルです。私は、コードを実行したときただし、tensorflowはエラーを与える：

Traceback (most recent call last): 
    File "C:\Program Files (x86)\JetBrains\PyCharm 2016.3\helpers\pydev\pydevd.py", line 1596, in <module> 
    globals = debugger.run(setup['file'], None, None, is_module) 
    File "C:\Program Files (x86)\JetBrains\PyCharm 2016.3\helpers\pydev\pydevd.py", line 974, in run 
    pydev_imports.execfile(file, globals, locals) # execute the script 
    File "C:\Program Files (x86)\JetBrains\PyCharm 2016.3\helpers\pydev\_pydev_imps\_pydev_execfile.py", line 18, in execfile 
    exec(compile(contents+"\n", file, 'exec'), glob, loc) 
    File "C:/Users/v-zhaom/OneDrive/speakerRNN/main.py", line 5, in <module> 
    speakerTagger.main() 
    File "C:/Users/v-zhaom/OneDrive/speakerRNN\speakerChangeTagger\tagger.py", line 152, in main 
    self.model = RecurrentModel(self.args, self.textData) 
    File "C:/Users/v-zhaom/OneDrive/speakerRNN\speakerChangeTagger\RecurrentModel.py", line 29, in __init__ 
    self.buildNetWork() 
    File "C:/Users/v-zhaom/OneDrive/speakerRNN\speakerChangeTagger\RecurrentModel.py", line 36, in buildNetWork 
    context_vectors = self._buildUttNetwork(last_outputs) 
    File "C:/Users/v-zhaom/OneDrive/speakerRNN\speakerChangeTagger\RecurrentModel.py", line 136, in _buildUttNetwork 
    tf.while_loop(cond=my_cond, body=add_inputs, loop_vars=[idx]) 
    File "C:\Python35\lib\site-packages\tensorflow\python\ops\control_flow_ops.py", line 2636, in while_loop 
    result = context.BuildLoop(cond, body, loop_vars, shape_invariants) 
    File "C:\Python35\lib\site-packages\tensorflow\python\ops\control_flow_ops.py", line 2469, in BuildLoop 
    pred, body, original_loop_vars, loop_vars, shape_invariants) 
    File "C:\Python35\lib\site-packages\tensorflow\python\ops\control_flow_ops.py", line 2441, in _BuildLoop 
    next_vars.append(_AddNextAndBackEdge(m, v)) 
    File "C:\Python35\lib\site-packages\tensorflow\python\ops\control_flow_ops.py", line 635, in _AddNextAndBackEdge 
    v = ops.convert_to_tensor(v) 
    File "C:\Python35\lib\site-packages\tensorflow\python\framework\ops.py", line 669, in convert_to_tensor 
    ret = conversion_func(value, dtype=dtype, name=name, as_ref=as_ref) 
    File "C:\Python35\lib\site-packages\tensorflow\python\framework\constant_op.py", line 176, in _constant_tensor_conversion_function 
    return constant(v, dtype=dtype, name=name) 
    File "C:\Python35\lib\site-packages\tensorflow\python\framework\constant_op.py", line 165, in constant 
    tensor_util.make_tensor_proto(value, dtype=dtype, shape=shape, verify_shape=verify_shape)) 
    File "C:\Python35\lib\site-packages\tensorflow\python\framework\tensor_util.py", line 360, in make_tensor_proto 
    raise ValueError("None values not supported.") 
ValueError: None values not supported. 

Answer 1

bodyパラメータに渡された関数はテンソル値ではなく、Noneを返す必要があります。機能を次のように変更してみてください。 docsから

def add_inputs(idx): 
    utt_input = tf.slice(last_outputs, begin=[idx, 0], 
    size=[self.args.uttWindowSize, self.args.wordUnits]) 
    utt_inputs.append(utt_input) 
    return tf.constant(0 , dtype=tf.int32 , name="ret_val") #Dummy 

、

body is a callable returning a (possibly nested) tuple, namedtuple or list of tensors of the same arity (length and structure) and types as loop_vars.