python - 如何访问/操作 keras 模型中的张量元素？

Question

我想测试一个新的网络结构，它需要更改 keras 模型中张量的一些元素。如果我能找到一种方法将张量转换/复制到 numpy 数组，然后再将其转换回张量，那么我应该能够使模型工作。

我尝试使用 .eval() 方法将张量转换为 numpy 数组，但它给了我错误。我也将此模型与 keras-rl 的 DQN 代理一起使用，因此错误可能来自 keras-rl 使用模型的方式。这是我的代码：

def Filter_Features(F):
    sess = Session()
    with sess.as_default():
        F_np = F.eval()

    min_pos = np.argmin(F_np)
    F_np[min_pos] = 0

    return convert_to_tensor(F_np)

def create_model(nb_actions, num_frames=4):
    inputs = Input(shape = (num_frames,84,84))
    F = Conv2D(16,(8,8), activation='relu', strides=(4,4), data_format = "channels_first")(inputs)
    ...

    F_k = Lambda(Filter_Features)(F)

    actions = Dense(nb_actions, activation = 'linear')(F_k)

    nnf_model = Model(inputs = inputs, outputs = actions)

    return nnf_model

请注意，如果我删除了 lambda 层，代码就会运行，所以问题一定出在那里。我收到错误：

 File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/client/session.py", line 1356, in _do_call
    return fn(*args)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/client/session.py", line 1341, in _run_fn
    options, feed_dict, fetch_list, target_list, run_metadata)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/client/session.py", line 1429, in _call_tf_sessionrun
    run_metadata)
tensorflow.python.framework.errors_impl.FailedPreconditionError: Attempting to use uninitialized value conv2d_1/bias
     [[{{node conv2d_1/bias/read}}]]


During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "Atari_Test.py", line 32, in <module>
    model = Model_StackExchange.create_model(nb_actions = nb_actions)
  File "/Users/j/deep-rl/Model_StackExchange.py", line 26, in create_model
    F_k = Lambda(Filter_Features)(F)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/keras/engine/base_layer.py", line 457, in __call__
    output = self.call(inputs, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/keras/layers/core.py", line 687, in call
    return self.function(inputs, **arguments)
  File "/Users/j/deep-rl/Model_StackExchange.py", line 11, in Filter_Features
    F_np = F.eval()
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/framework/ops.py", line 731, in eval
    return _eval_using_default_session(self, feed_dict, self.graph, session)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/framework/ops.py", line 5579, in _eval_using_default_session
    return session.run(tensors, feed_dict)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/client/session.py", line 950, in run
    run_metadata_ptr)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/client/session.py", line 1173, in _run
    feed_dict_tensor, options, run_metadata)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/client/session.py", line 1350, in _do_run
    run_metadata)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/client/session.py", line 1370, in _do_call
    raise type(e)(node_def, op, message)
tensorflow.python.framework.errors_impl.FailedPreconditionError: Attempting to use uninitialized value conv2d_1/bias
     [[node conv2d_1/bias/read (defined at /Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/keras/backend/tensorflow_backend.py:402) ]]

Original stack trace for 'conv2d_1/bias/read':
  File "Atari_Test.py", line 32, in <module>
    model = Model_StackExchange.create_model(nb_actions = nb_actions)
  File "/Users/j/deep-rl/Model_StackExchange.py", line 21, in create_model
    F = Conv2D(16,(8,8), activation='relu', strides=(4,4), data_format = "channels_first")(inputs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/keras/engine/base_layer.py", line 431, in __call__
    self.build(unpack_singleton(input_shapes))
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/keras/layers/convolutional.py", line 147, in build
    constraint=self.bias_constraint)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/keras/legacy/interfaces.py", line 91, in wrapper
    return func(*args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/keras/engine/base_layer.py", line 252, in add_weight
    constraint=constraint)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/keras/backend/tensorflow_backend.py", line 402, in variable
    v = tf.Variable(value, dtype=tf.as_dtype(dtype), name=name)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/ops/variables.py", line 259, in __call__
    return cls._variable_v1_call(*args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/ops/variables.py", line 220, in _variable_v1_call
    shape=shape)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/ops/variables.py", line 198, in <lambda>
    previous_getter = lambda **kwargs: default_variable_creator(None, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/ops/variable_scope.py", line 2511, in default_variable_creator
    shape=shape)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/ops/variables.py", line 263, in __call__
    return super(VariableMetaclass, cls).__call__(*args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/ops/variables.py", line 1568, in __init__
    shape=shape)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/ops/variables.py", line 1755, in _init_from_args
    self._snapshot = array_ops.identity(self._variable, name="read")
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/util/dispatch.py", line 180, in wrapper
    return target(*args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/ops/array_ops.py", line 86, in identity
    ret = gen_array_ops.identity(input, name=name)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/ops/gen_array_ops.py", line 4253, in identity
    "Identity", input=input, name=name)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/framework/op_def_library.py", line 788, in _apply_op_helper
    op_def=op_def)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/util/deprecation.py", line 507, in new_func
    return func(*args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/framework/ops.py", line 3616, in create_op
    op_def=op_def)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/tensorflow/python/framework/ops.py", line 2005, in __init__
    self._traceback = tf_stack.extract_stack()

如果您知道如何访问和更改 keras 模型中张量的元素，请告诉我。谢谢你。

标签： pythontensorflowkerasreinforcement-learningkeras-rl