18.Keras与Tensorflow混用(再战VAE)

Tensorflow : 1.9.0

import tensorflow as tf
import keras
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.gridspec as gridspec
import keras.backend as K
import os
from keras.layers import Dense,Dropout
from tensorflow.examples.tutorials.mnist import input_data
mnist = input_data.read_data_sets('MNIST_data/',one_hot=True)

if not os.path.exists('out/'):
    os.makedirs('out/')

#画图方法
def plot(samples):
    fig = plt.figure(figsize=(4, 4))
    gs = gridspec.GridSpec(4, 4)
    gs.update(wspace=0.05, hspace=0.05)

    for i, sample in enumerate(samples):
        ax = plt.subplot(gs[i])
        plt.axis('off')
        ax.set_xticklabels([])
        ax.set_yticklabels([])
        ax.set_aspect('equal')
        plt.imshow(sample.reshape(28, 28), cmap='Greys_r')
    return fig

#输入维度
input_dim = 784
#隐变量z的维度
z_dim = 2
#学习率
learning_rate = 0.001
#minibatch的大小
batch_size = 250

#定义占位符
X = tf.placeholder(tf.float32, shape=[None, input_dim])
z = tf.placeholder(tf.float32, shape=[None, z_dim])
X /= 255.

#编码层
encode = Dense(512,activation='relu',
               kernel_initializer=keras.initializers.TruncatedNormal())(X)
encode = Dense(256,activation='relu',
               kernel_initializer=keras.initializers.TruncatedNormal())(encode)
encode = Dropout(rate=0.3)(encode)
mu = Dense(z_dim,
           kernel_initializer=keras.initializers.TruncatedNormal())(encode)
logvar = Dense(z_dim,
               kernel_initializer=keras.initializers.TruncatedNormal())(encode)

#计算Z
def get_z(z_mu,z_logvar):
    #标准正态分布
    eps = tf.random_normal(shape=tf.shape(z_mu))
    #返回Z的分布
    return mu + tf.exp(z_logvar / 2) * eps

z = get_z(mu,logvar)

decode = Dense(256,activation='relu',
               kernel_initializer=keras.initializers.TruncatedNormal())(z)
decode = Dense(512,activation='relu',
               kernel_initializer=keras.initializers.TruncatedNormal())(decode)
decode = Dropout(rate=0.3)(decode)
x_samples = Dense(784,activation='sigmoid')(decode)

#重构损失,比较还原的图像与原图像的损失
BCE = K.sum(K.binary_crossentropy(X,x_samples),axis=1)
#KL散度
KLD = 0.5*K.sum(tf.pow(mu, 2) + K.exp(logvar) - 1 - logvar,1)
# VAE loss
vae_loss = K.mean(KLD + BCE)

train = tf.train.AdamOptimizer(learning_rate).minimize(vae_loss)

with tf.Session() as sess:
    sess.run(tf.global_variables_initializer())
    i = 10
    for it in range(5001): 
        batch_xs, _ = mnist.train.next_batch(batch_size) 
        _, loss = sess.run([train, vae_loss], feed_dict={X: batch_xs})
        if it % 1000 == 0:
            print('Iter: {}'.format(it))
            print('Loss: {:.4}'. format(loss))
            print('-----------------------')
            samples = sess.run(x_samples, feed_dict={z:np.random.randn(16, z_dim)})
            fig = plot(samples)
            plt.savefig('out/{}.png'.format(str(i).zfill(3)), bbox_inches='tight')
            i += 1
            plt.close(fig)

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