Keras多輸入AttributeError：'NoneType'對象沒有屬性'inbound_nodes'

Question

我試圖建立一個模型，如下圖所示。這個想法是採用多個分類特徵（一個熱點向量）並將它們分開嵌入，然後將這些嵌入向量與一個LSTM的3D張量結合起來。

隨着以下代碼Keras2.0.2，創建具有多個輸入的Model()對象時，它會引發類似於this問題的AttributeError: 'NoneType' object has no attribute 'inbound_nodes'。任何人都可以幫我弄清楚有什麼問題嗎？

型號：

代碼：

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' 

Answer 1

keras.backend.repeat是一個函數，而不是一個層。嘗試使用keras.layers.core.RepeatVector代替。它具有與該功能相同的功能。

emd_out_3d = RepeatVector(10)(emd_out)