add_loss in Keras/Tensorflow 的两种不同方法不能一起使用吗？

Question

我写了下面的代码来通过自动编码器做一个简单的实验，我只想使用两个损失，第一个损失是输入的传统 MSE 损失和从潜在向量重建的输出AE，第二个loss是encoder和decoder中对称层的两个输出之间的MSE loss，也就是说如果AE有5层，我想在第二层和第四层之间加一个MSE loss层，因为它们是 symmetrical.The 代码在这里：

from time import time
import numpy as np
import random
from keras.models import Model
import keras.backend as K
from keras.engine.topology import Layer, InputSpec
from keras.layers import Dense, Input, GaussianNoise, Layer, Activation
from keras.models import Model
from keras.optimizers import SGD, Adam
from keras.utils.vis_utils import plot_model
from keras.callbacks import EarlyStopping

#build vae model

input_place = Input(shape=(128,))

e_layer1 = Dense(64,activation='relu')(input_place)
e_layer2 = Dense(32,activation='relu')(e_layer1)
hidden = Dense(16,activation='relu')(e_layer2)

d_layer1 = Dense(32,activation='relu')(hidden)
d_layer2 = Dense(64,activation='relu')(d_layer1)

output_place = Dense(128,activation='sigmoid')(d_layer2)

model = Model(inputs=input_place,outputs=output_place)

loss = K.mean(K.square(d_layer1 - e_layer2),axis = -1)

model.add_loss(loss)

model.compile(optimizer = 'adam',
              loss=['mse'],
              metrics=['accuracy'])

input_data = np.random.randn(400,128)

model.fit(input_data,
          input_data,
          batch_size = 32,
          epochs=5)

但是当我运行这段代码时，它发生了关于

的错误

Epoch 1/5
 32/400 [=>............................] - ETA: 12s - loss: 1.6429 - acc: 0.0000e+00Traceback (most recent call last):

  File "<ipython-input-49-eac3a65824ec>", line 1, in <module>
    runfile('/Users/jishilun/Desktop/keras_loss_test.py', wdir='/Users/jishilun/Desktop')

  File "/anaconda3/lib/python3.7/site-packages/spyder_kernels/customize/spydercustomize.py", line 704, in runfile
    execfile(filename, namespace)

  File "/anaconda3/lib/python3.7/site-packages/spyder_kernels/customize/spydercustomize.py", line 108, in execfile
    exec(compile(f.read(), filename, 'exec'), namespace)

  File "/Users/jishilun/Desktop/keras_loss_test.py", line 49, in <module>
    epochs=5)

  File "/anaconda3/lib/python3.7/site-packages/keras/engine/training.py", line 1039, in fit
    validation_steps=validation_steps)

  File "/anaconda3/lib/python3.7/site-packages/keras/engine/training_arrays.py", line 204, in fit_loop
    callbacks.on_batch_end(batch_index, batch_logs)

  File "/anaconda3/lib/python3.7/site-packages/keras/callbacks.py", line 115, in on_batch_end
    callback.on_batch_end(batch, logs)

  File "/anaconda3/lib/python3.7/site-packages/keras/callbacks.py", line 236, in on_batch_end
    self.totals[k] += v * batch_size

ValueError: operands could not be broadcast together with shapes (32,) (16,) (32,)

如果我删除add_loss，代码可以运行，所以我认为Keras/Tensorflow中add_loss的两种方法不能简单地一起使用或者它可能有一些变化（也许问题来自小批量？）请帮我！欢迎任何意见或建议！非常感谢！

Answer 1

问题不是出自 add_loss()，而是出自您的 batch_size。你输入的数据是(400,128)，但是batch_size是32，试试改成400的因数，比如40或者20，就可以了。

add_loss in Keras/Tensorflow 的两种不同方法不能一起使用吗？

Can't the two different methods to add_loss in Keras/Tensorflow be used together?

loss

autoencoder

keras

tensorflow