Question

我正在浏览keras博客，发现其中一个simple autoencoderes。它是使用keras编写的，并且按预期运行。

我对代码进行了一些更改以使用tensorflow 2 keras功能API。现在的问题是代码没有抛出任何错误，但是没有按预期运行（Val损失大于0.6）。

我在代码中找不到任何错误。这是修改后的代码：

from tensorflow.keras.layers import Dense, Input
from tensorflow import keras
from tensorflow.keras.datasets import mnist
import numpy as np

encoding_dim = 32


input_img = Input(shape=(784,))
encoded = Dense(encoding_dim, activation='relu')(input_img)
decoded = Dense(784, activation='sigmoid')(encoded)

autoencoder = keras.Model(input_img, decoded)

encoder = keras.Model(input_img, encoded)

encoded_input = Input(shape=(encoding_dim,))
decoder_layer = autoencoder.layers[-1]
decoder = keras.Model(encoded_input, decoder_layer(encoded_input))

autoencoder.compile(optimizer='adadelta', loss='binary_crossentropy')


(x_train, _), (x_test, _) = mnist.load_data()

x_train = x_train.astype('float32') / 255.
x_test = x_test.astype('float32') / 255.
x_train = x_train.reshape((len(x_train), np.prod(x_train.shape[1:])))
x_test = x_test.reshape((len(x_test), np.prod(x_test.shape[1:])))
print(x_train.shape)
print(x_test.shape)

autoencoder.fit(x_train, x_train,
               epochs=50,
               batch_size=256,
               shuffle=True,
               validation_data=(x_test, x_test))

encoded_imgs = encoder.predict(x_test)
decoded_imgs = decoder.predict(encoded_imgs)


# use Matplotlib (don't ask)
import matplotlib.pyplot as plt

n = 10  # how many digits we will display
plt.figure(figsize=(20, 4))
for i in range(n):
    # display original
    ax = plt.subplot(2, n, i + 1)
    plt.imshow(x_test[i].reshape(28, 28))
    plt.gray()
    ax.get_xaxis().set_visible(False)
    ax.get_yaxis().set_visible(False)

    # display reconstruction
    ax = plt.subplot(2, n, i + 1 + n)
    plt.imshow(decoded_imgs[i].reshape(28, 28))
    plt.gray()
    ax.get_xaxis().set_visible(False)
    ax.get_yaxis().set_visible(False)
plt.show()

Answer 1

如果将优化器更改为adam，则损失函数会收敛。还要检查这个问题：

Ada-Delta method doesn't converge when used in Denoising AutoEncoder with MSE loss & ReLU activation?

Tensorflow自动编码器损耗不收敛

1 个答案: