AttributeError: 'NoneType' object has no attribute '_inbound_nodes' in Keras

Question

I want to define my own Lstm model as follows:

from keras import backend as K
from keras.callbacks import ModelCheckpoint
from keras.layers.core import Dense, Ac         


        

Answer 1

You should use keras.layers.Lambda to wrap K.* operations as a layer instead of K.* function directly.

# change
avg_pool = K.mean(rnn_outputs, axis = 1)
max_pool = K.max(rnn_outputs, axis = 1)
# to
avg_pool = Lambda(lambda x:K.mean(x,axis=1))(rnn_outputs)
max_pool = Lambda(lambda x:K.max(x,axis=1))(rnn_outputs)