ValueError:尝试将不支持类型（<class'NoneType'>）的值（None）转换为张量。展平层

Question

我正在尝试使用Keras的VGG16，我标记了include_top=false
但我面临的错误是ValueError: Attempt to convert a value (None) with an unsupported type (<class 'NoneType'>) to a Tensor.
下面是代码：

input_shape = (150,150,3)
model_1 = VGG16(weights='imagenet',include_top=False,input_shape=input_shape)
Last_layer=model_1.layers[-1].output
print(Last_layer)
print(type(Last_layer))
Model_Vgg=keras.layers.Flatten()(Last_layer) #<---- error rised here
 
#Model_Vgg=keras.Model(model.input,layer_output)

Model_Vgg = layers.Dropout(0.5)(Model_Vgg)


Model_Vgg = layers.Dense(units=3, activation='softmax') (Model_Vgg)

model = keras.Model(inputs =model_1.input,outputs = Model_Vgg )
model.compile(loss='categorical_crossentropy',optimizer=optimizers.SGD(lr=0.005708),metrics=['accuracy'])

monitor = EarlyStopping(monitor='accuracy',patience=50, mode='auto', restore_best_weights=True)
model.fit(X_Train,Y_Train,callbacks=[monitor],epochs=280,verbose=0)
(loss, accuracy) = model.evaluate(X_Test, Y_Test, batch_size=32, verbose=50)
print("[INFO] loss={:.4f}, accuracy: {:.4f}%".format(loss,accuracy * 100)) 

它表明print(type(Last_layer)) =<class 'keras.engine.keras_tensor.KerasTensor'>
我不知道为什么这行引用了None-type对象

Answer 1

我对代码也有同样的问题：

from keras.layers import Dense, Flatten
x = vgg.output(Flatten())

然后我把它改成了

from tensorflow.keras import layers
x = layers.Flatten()(vgg.output)

它成功了