<p>我使用了不同的方法来定义VAE损失,如中所示:</p>
<p><a href="https://github.com/keras-team/keras/blob/keras-2/examples/variational_autoencoder.py" rel="nofollow noreferrer">https://github.com/keras-team/keras/blob/keras-2/examples/variational_autoencoder.py</a></p>
<p>我修改了它以允许数据去噪。
它现在可以工作了,但是我必须使用超参数来正确地重建原始图像。在</p>
<pre><code>import numpy as np
import time
import sys
import os
from scipy.stats import norm
from keras.layers import Input, Dense, Lambda
from keras.models import Model
from keras import backend as K
from keras import metrics
from keras.datasets import mnist
from keras.callbacks import ModelCheckpoint
filepath_for_w='denoise_by_VAE_weights_1.h5'
###########
##########
experiment_dir= 'exp_'+str(int(time.time()))
os.mkdir(experiment_dir)
this_script=sys.argv[0]
from shutil import copyfile
copyfile(this_script, experiment_dir+'/'+this_script)
##########
###########
batch_size = 100
original_dim = 784
latent_dim = 2
intermediate_dim = 256
epochs = 10
epsilon_std = 1.0
x = Input(batch_shape=(batch_size, original_dim))
h = Dense(intermediate_dim, activation='relu')(x)
z_mean = Dense(latent_dim)(h)
z_log_var = Dense(latent_dim)(h)
def sampling(args):
z_mean, z_log_var = args
epsilon = K.random_normal(shape=(batch_size, latent_dim), mean=0.,
stddev=epsilon_std)
return z_mean + K.exp(z_log_var / 2) * epsilon
# note that "output_shape" isn't necessary with the TensorFlow backend
z = Lambda(sampling, output_shape=(latent_dim,))([z_mean, z_log_var])
# we instantiate these layers separately so as to reuse them later
decoder_h = Dense(intermediate_dim, activation='relu')
decoder_mean = Dense(original_dim, activation='sigmoid')
h_decoded = decoder_h(z)
x_decoded_mean = decoder_mean(h_decoded)
def vae_loss(x, x_decoded_mean):
xent_loss = original_dim * metrics.binary_crossentropy(x, x_decoded_mean)
kl_loss = - 0.5 * K.sum(1 + z_log_var - K.square(z_mean) - K.exp(z_log_var), axis=-1)
return xent_loss + kl_loss
vae = Model(x, x_decoded_mean)
vae.compile(optimizer='rmsprop', loss=vae_loss)
# train the VAE on MNIST digits
(x_train, y_train), (x_test, y_test) = mnist.load_data()
#after loading the data, change to the new experiment dir
os.chdir(experiment_dir) #
##########################
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:])))
noise_factor = 0.5
x_test_noisy = x_test + noise_factor * np.random.normal(loc=0.0, scale=1.0, size=x_test.shape)
x_test_noisy = np.clip(x_test_noisy, 0., 1.)
for i in range (10):
x_train_noisy = x_train + noise_factor * np.random.normal(loc=0.0, scale=1.0, size=x_train.shape)
x_train_noisy = np.clip(x_train_noisy, 0., 1.)
checkpointer=ModelCheckpoint(filepath_for_w, monitor='val_loss', verbose=0, save_best_only=True, save_weights_only=True, mode='auto', period=1)
vae.fit(x_train_noisy, x_train,
shuffle=True,
epochs=epochs,
batch_size=batch_size,
validation_data=(x_test_noisy, x_test),
callbacks=[checkpointer])
vae.load_weights(filepath_for_w)
#print (x_train.shape)
#print (x_test.shape)
decoded_imgs = vae.predict(x_test,batch_size=batch_size)
np.save('decoded'+str(i)+'.npy',decoded_imgs)
np.save('tested.npy',x_test_noisy)
#np.save ('true_catagories.npy',y_test)
np.save('original.npy',x_test)
</code></pre>