我已经用CNN训练了一个二元分类模型,下面是我的代码
model = Sequential()
model.add(Convolution2D(nb_filters, kernel_size[0], kernel_size[1],
border_mode='valid',
input_shape=input_shape))
model.add(Activation('relu'))
model.add(Convolution2D(nb_filters, kernel_size[0], kernel_size[1]))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=pool_size))
# (16, 16, 32)
model.add(Convolution2D(nb_filters*2, kernel_size[0], kernel_size[1]))
model.add(Activation('relu'))
model.add(Convolution2D(nb_filters*2, kernel_size[0], kernel_size[1]))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=pool_size))
# (8, 8, 64) = (2048)
model.add(Flatten())
model.add(Dense(1024))
model.add(Activation('relu'))
model.add(Dropout(0.5))
model.add(Dense(2)) # define a binary classification problem
model.add(Activation('softmax'))
model.compile(loss='categorical_crossentropy',
optimizer='adadelta',
metrics=['accuracy'])
model.fit(x_train, y_train,
batch_size=batch_size,
nb_epoch=nb_epoch,
verbose=1,
validation_data=(x_test, y_test))
这里,我想要得到每一层的输出就像TensorFlow一样,我该怎么做呢?
你可以通过使用:model.layers[index].output轻松获得任何层的输出
对于所有层使用这个:
from keras import backend as K
inp = model.input # input placeholder
outputs = [layer.output for layer in model.layers] # all layer outputs
functors = [K.function([inp, K.learning_phase()], [out]) for out in outputs] # evaluation functions
# Testing
test = np.random.random(input_shape)[np.newaxis,...]
layer_outs = [func([test, 1.]) for func in functors]
print layer_outs
注意:要模拟Dropout,请使用learning_phase作为1。在layer_outs中,否则使用0。
编辑:(根据评论)
K.function创建了ano/tensorflow张量函数,之后用于从给定输入的符号图中获得输出。
现在需要K.learning_phase()作为输入,因为许多Keras层(如Dropout/Batchnomalization)依赖它来改变训练和测试期间的行为。
所以如果你在你的代码中删除dropout层,你可以简单地使用:
from keras import backend as K
inp = model.input # input placeholder
outputs = [layer.output for layer in model.layers] # all layer outputs
functors = [K.function([inp], [out]) for out in outputs] # evaluation functions
# Testing
test = np.random.random(input_shape)[np.newaxis,...]
layer_outs = [func([test]) for func in functors]
print layer_outs
编辑2:更优化
我刚刚意识到,前面的答案并没有优化,因为对于每个函数的计算,数据将被CPU->GPU内存传输,而且张量计算需要对较低的层进行n-over。
相反,这是一种更好的方式,因为你不需要多个函数,而是一个函数给你所有输出的列表:
from keras import backend as K
inp = model.input # input placeholder
outputs = [layer.output for layer in model.layers] # all layer outputs
functor = K.function([inp, K.learning_phase()], outputs ) # evaluation function
# Testing
test = np.random.random(input_shape)[np.newaxis,...]
layer_outs = functor([test, 1.])
print layer_outs