Keras 多输入 AttributeError：“NoneType”对象没有属性“inbound_nodes”

我正在尝试构建一个模型，如下图所示。这个想法是采用多个分类特征（one-hot 向量）并分别嵌入它们，然后将这些嵌入向量与 LSTM 的 3D 张量组合起来。

在以下代码中Keras2.0.2，当创建Model()具有多个输入的对象，它会引发AttributeError: 'NoneType' object has no attribute 'inbound_nodes'如同this https://stackoverflow.com/questions/44109127/multi-input-and-multi-output-models-based-on-keras2-0问题。谁能帮我找出问题所在吗？

Model:

Code:

from keras.layers import Dense, LSTM, Input
from keras.layers.merge import concatenate
from keras import backend as K
from keras.models import Model

cat_feats_dims = [315, 14] # Dimensions of the cat_feats
emd_inputs = [Input(shape=(in_size,)) for in_size in cat_feats_dims]
emd_out = concatenate([Dense(20, use_bias=False)(inp) for inp in emd_inputs])
emd_out_3d = K.repeat(emd_out, 10)

lstm_input = Input(shape=(10,5))

merged = concatenate([emd_out_3d,lstm_input])

lstm_output = LSTM(32)(merged)
dense_output = Dense(1, activation='linear')(lstm_output)

model = Model(inputs=emd_inputs+[lstm_input], outputs=[dense_output])

#ERROR MESSAGE
Traceback (most recent call last):
  File "C:\Program Files\Anaconda2\envs\mle-env\lib\site-packages\IPython\core\interactiveshell.py", line 2881, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-2-a9da7f276aa7>", line 14, in <module>
    model = Model(inputs=emd_inputs+[lstm_input], outputs=[dense_output])
  File "C:\Program Files\Anaconda2\envs\mle-env\lib\site-packages\keras\legacy\interfaces.py", line 88, in wrapper
    return func(*args, **kwargs)
  File "C:\Program Files\Anaconda2\envs\mle-env\lib\site-packages\keras\engine\topology.py", line 1648, in __init__
    build_map_of_graph(x, seen_nodes, depth=0)
  File "C:\Program Files\Anaconda2\envs\mle-env\lib\site-packages\keras\engine\topology.py", line 1644, in build_map_of_graph
    layer, node_index, tensor_index)
  File "C:\Program Files\Anaconda2\envs\mle-env\lib\site-packages\keras\engine\topology.py", line 1644, in build_map_of_graph
    layer, node_index, tensor_index)
  File "C:\Program Files\Anaconda2\envs\mle-env\lib\site-packages\keras\engine\topology.py", line 1639, in build_map_of_graph
    next_node = layer.inbound_nodes[node_index]
AttributeError: 'NoneType' object has no attribute 'inbound_nodes'

keras.backend.repeat 是一个函数，而不是一个层。尝试使用keras.layers.core.RepeatVector https://keras.io/layers/core/#repeatvector反而。它具有与函数相同的功能。

emd_out_3d = RepeatVector(10)(emd_out)