GAN.py

#-*- coding: utf-8 -*-
from __future__ import division
import os
import time
import tensorflow as tf
import numpy as np

from ops import *
from utils import *

class GAN(object):
    #初始化各类定义
    def __init__(self, sess, epoch, batch_size, z_dim, dataset_name, checkpoint_dir, result_dir, log_dir):
        self.sess = sess
        self.dataset_name = dataset_name
        self.checkpoint_dir = checkpoint_dir
        self.result_dir = result_dir
        self.log_dir = log_dir
        self.epoch = epoch
        self.batch_size = batch_size
        self.model_name = "GAN"     # name for checkpoint

        #mnist和fashion-mnist都是由28x28的灰色图像组成的
        if dataset_name == 'mnist' or dataset_name == 'fashion-mnist':
            # parameters
            self.input_height = 28
            self.input_width = 28
            self.output_height = 28
            self.output_width = 28

            self.z_dim = z_dim         # dimension of noise-vector
            self.c_dim = 1

            # train
            self.learning_rate = 0.0002
            self.beta1 = 0.5

            # test
            self.sample_num = 64  # number of generated images to be saved,保存图片的数量

            # load mnist, data_X为mnist数据图片归一化结果，data_y为加上标签的数组记录。
            self.data_X, self.data_y = load_mnist(self.dataset_name)

            # get number of batches for a single epoch 在单个批次下处理的数据长度，此处为70000整除64=1093
            self.num_batches = len(self.data_X) // self.batch_size
        else:
            raise NotImplementedError

    #送入鉴别器的输入为(64,28,28,1)
    def discriminator(self, x, is_training=True, reuse=False):
        # Network Architecture is exactly same as in infoGAN (https://arxiv.org/abs/1606.03657)
        # Architecture : (64)4c2s-(128)4c2s_BL-FC1024_BL-FC1_S
        with tf.variable_scope("discriminator", reuse=reuse):
            # 经过这一步卷积后，(64,28,28,1)-->(64,14,14,64)
            net = lrelu(conv2d(x, 64, 4, 4, 2, 2, name='d_conv1'))
            # 经过这一步卷积后，(64,14,14,64)-->(64,7,7,128)
            net = lrelu(bn(conv2d(net, 128, 4, 4, 2, 2, name='d_conv2'), is_training=is_training, scope='d_bn2'))#数据标准化
            #经过数组重构后，(64,7,7,128)-->(64,6272)
            net = tf.reshape(net, [self.batch_size, -1])
            #经过线性处理后将矩阵，(64,6272)-->(64,1024)
            net = lrelu(bn(linear(net, 1024, scope='d_fc3'), is_training=is_training, scope='d_bn3'))
            #经过线性处理后将矩阵，(64,1024)-->(64,1)
            out_logit = linear(net, 1, scope='d_fc4')
            #将数据处理在（0,1）之间
            out = tf.nn.sigmoid(out_logit)

            return out, out_logit, net

    # 送入生成器的输入噪声z为(64,62)
    def generator(self, z, is_training=True, reuse=False):
        # Network Architecture is exactly same as in infoGAN (https://arxiv.org/abs/1606.03657)
        # Architecture : FC1024_BR-FC7x7x128_BR-(64)4dc2s_BR-(1)4dc2s_S
        with tf.variable_scope("generator", reuse=reuse):
            # 经过线性处理后将矩阵，(64,62)-->(64,1024)
            net = tf.nn.relu(bn(linear(z, 1024, scope='g_fc1'), is_training=is_training, scope='g_bn1'))
            # 经过线性处理后将矩阵，(64,1024)-->(64,6272), 6272=128*7*7
            net = tf.nn.relu(bn(linear(net, 128 * 7 * 7, scope='g_fc2'), is_training=is_training, scope='g_bn2'))
            # 经过重构后，形状变为(64,7,7,128)
            net = tf.reshape(net, [self.batch_size, 7, 7, 128])
            # 经过deconv2d,(64,7,7,128)-->(64,14,14,128)
            net = tf.nn.relu(
                bn(deconv2d(net, [self.batch_size, 14, 14, 64], 4, 4, 2, 2, name='g_dc3'), is_training=is_training,
                   scope='g_bn3'))
            # 经过deconv2d,(64,14,14,128)-->(64,28,28,1),将值处理用sigmoid处理至（0,1）之间,`y = 1 / (1 + exp(-x))`
            out = tf.nn.sigmoid(deconv2d(net, [self.batch_size, 28, 28, 1], 4, 4, 2, 2, name='g_dc4'))

            return out

    #建立GAN模型，此函数非常重要
    def build_model(self):
        # some parameters
        # 对于mnist数据集，图片大小为（28,28,1），此处用list列表存储
        image_dims = [self.input_height, self.input_width, self.c_dim]
        bs = self.batch_size

        """ Graph Input """
        # images (64,28,28,1)
        self.inputs = tf.placeholder(tf.float32, [bs] + image_dims, name='real_images')

        # noises (64,62)
        self.z = tf.placeholder(tf.float32, [bs, self.z_dim], name='z')

        """ Loss Function """

        # output of D for real images, D_real((64,1),介于(0,1)),D_real_logits未经历过sigmoid，_临时存储net(64,1024)
        D_real, D_real_logits, _ = self.discriminator(self.inputs, is_training=True, reuse=False)

        # output of D for fake images G为由噪声z（64,62）生成的图片数据(64,28,28,1)
        G = self.generator(self.z, is_training=True, reuse=False)
        #D_fake((64,1),介于(0,1)),D_fake_logits未经历过sigmoid，_临时存储net(64,1024),送入鉴别器的是G生成的假的数据
        D_fake, D_fake_logits, _ = self.discriminator(G, is_training=True, reuse=True)

        # get loss for discriminator
        #它对于输入的logits先通过sigmoid函数计算，再计算它们的交叉熵，但是它对交叉熵的计算方式进行了优化，使得结果不至于溢出
        #tf.ones_like的使用默认交叉商前面的系数为1数组
        #d_loss_real=-log(sigmoid(D_real_logits))等价于d_loss_real=-log(D(x))
        d_loss_real = tf.reduce_mean(
            tf.nn.sigmoid_cross_entropy_with_logits(logits=D_real_logits, labels=tf.ones_like(D_real)))
        # d_loss_fake=-log(sigmoid(D_fake_logits))等价于d_loss_fake=-log(D(G(z))
        d_loss_fake = tf.reduce_mean(
            tf.nn.sigmoid_cross_entropy_with_logits(logits=D_fake_logits, labels=tf.zeros_like(D_fake)))
        #d_loss为生成器和鉴别器传出的loss之和
        self.d_loss = d_loss_real + d_loss_fake

        # get loss for generator
        #g_loss=-log(sigmoid(D_fake_logits))等价于g_loss=-log(D(G(z))
        self.g_loss = tf.reduce_mean(
            tf.nn.sigmoid_cross_entropy_with_logits(logits=D_fake_logits, labels=tf.ones_like(D_fake)))

        """ Training """
        # divide trainable variables into a group for D and a group for G
        t_vars = tf.trainable_variables()
        d_vars = [var for var in t_vars if 'd_' in var.name]
        g_vars = [var for var in t_vars if 'g_' in var.name]

        # optimizers 优化器用于减小损失函数loss，采用Adam优化器，可直接用minimize
        with tf.control_dependencies(tf.get_collection(tf.GraphKeys.UPDATE_OPS)):
            self.d_optim = tf.train.AdamOptimizer(self.learning_rate, beta1=self.beta1) \
                      .minimize(self.d_loss, var_list=d_vars)
            self.g_optim = tf.train.AdamOptimizer(self.learning_rate*5, beta1=self.beta1) \
                      .minimize(self.g_loss, var_list=g_vars)

        """" Testing """
        # for test 由噪声生成一张图片
        self.fake_images = self.generator(self.z, is_training=False, reuse=True)

        """ Summary """
        #Summary的含义是将参数打包后用于tensorboard的观察和模型的记录
        d_loss_real_sum = tf.summary.scalar("d_loss_real", d_loss_real)
        d_loss_fake_sum = tf.summary.scalar("d_loss_fake", d_loss_fake)
        d_loss_sum = tf.summary.scalar("d_loss", self.d_loss)
        g_loss_sum = tf.summary.scalar("g_loss", self.g_loss)

        # final summary operations
        self.g_sum = tf.summary.merge([d_loss_fake_sum, g_loss_sum])
        self.d_sum = tf.summary.merge([d_loss_real_sum, d_loss_sum])

    #最为重要的一个函数，控制着GAN模型的训练
    def train(self):

        # initialize all variables初始化各个变量
        tf.global_variables_initializer().run()

        # graph inputs for visualize training results
        #创造噪声z,GAN中应用的为均值分布，创造(64,62)大小的-1到1之间的
        self.sample_z = np.random.uniform(-1, 1, size=(self.batch_size, self.z_dim))

        # saver to save model 将训练好的模型参数保存起来
        self.saver = tf.train.Saver()

        # summary writer 将训练记录在log下
        self.writer = tf.summary.FileWriter(self.log_dir + '/' + self.model_name, self.sess.graph)

        # restore check-point if it exits
        could_load, checkpoint_counter = self.load(self.checkpoint_dir)
        if could_load:
            start_epoch = int(checkpoint_counter / self.num_batches)
            start_batch_id = checkpoint_counter - start_epoch * self.num_batches
            counter = checkpoint_counter
            print(" [*] Load SUCCESS")
        else:
            start_epoch = 0
            start_batch_id = 0
            counter = 1
            print(" [!] Load failed...")

        # loop for epoch
        start_time = time.time()
        for epoch in range(start_epoch, self.epoch):

            # get batch data
            # 由于batchsize为64，遍历70000张图片需要1093次
            for idx in range(start_batch_id, self.num_batches):
                #提取处理好的固定位置图片，data_X的按批次处理后的图片位置，一个批次64张图片
                batch_images = self.data_X[idx*self.batch_size:(idx+1)*self.batch_size]
                #构造均匀分布的噪声z
                batch_z = np.random.uniform(-1, 1, [self.batch_size, self.z_dim]).astype(np.float32)

                # update D network sess.run喂入数据优化更新D网络，并在tensorboard中更新
                _, summary_str, d_loss = self.sess.run([self.d_optim, self.d_sum, self.d_loss],
                                               feed_dict={self.inputs: batch_images, self.z: batch_z})
                self.writer.add_summary(summary_str, counter)

                # update G network sess.run喂入数据优化更新G网络，并在tensorboard中更新
                _, summary_str, g_loss = self.sess.run([self.g_optim, self.g_sum, self.g_loss], feed_dict={self.z: batch_z})
                self.writer.add_summary(summary_str, counter)

                # display training status
                counter += 1
                #训练一个batchsize打印一下loss，一个epoch打印1093次我认为没这个必要,50次batchsize后打印一下
                if np.mod(counter, 50) == 0:
                    print("Epoch: [%2d] [%4d/%4d] time: %4.4f, d_loss= %.8f, g_loss= %.8f" \
                          % (epoch, idx, self.num_batches, time.time() - start_time, d_loss, g_loss))

                # save training results for every 300 steps 训练300步保存一张图片
                if np.mod(counter, 300) == 0:
                    #生成一张该阶段下的由生成器生成的“假图片”
                    samples = self.sess.run(self.fake_images, feed_dict={self.z: self.sample_z})
                    #此处计算生成图片的小框图片的排布，本处为8×8排布
                    tot_num_samples = min(self.sample_num, self.batch_size)
                    manifold_h = int(np.floor(np.sqrt(tot_num_samples)))
                    manifold_w = int(np.floor(np.sqrt(tot_num_samples)))
                    save_images(samples[:manifold_h * manifold_w, :, :, :], [manifold_h, manifold_w],
                                './' + check_folder(self.result_dir + '/' + self.model_dir) + '/' + self.model_name +
                                '_train_{:02d}_{:04d}.png'.format(epoch, idx))

            # After an epoch, start_batch_id is set to zero 经过一个epoch后start_batch_id置为0
            # non-zero value is only for the first epoch after loading pre-trained model
            start_batch_id = 0

            # save model
            self.save(self.checkpoint_dir, counter)

            # show temporal results 经过一个epoch后输出一张全类别的图片，用于比较epoch后的差别
            self.visualize_results(epoch)

        # save model for final step 当epoch全部训练完后保存checkpoint
        self.save(self.checkpoint_dir, counter)

    #用于可视化epoch后输出图片
    def visualize_results(self, epoch):
        tot_num_samples = min(self.sample_num, self.batch_size)
        image_frame_dim = int(np.floor(np.sqrt(tot_num_samples)))

        """ random condition, random noise """

        z_sample = np.random.uniform(-1, 1, size=(self.batch_size, self.z_dim))

        samples = self.sess.run(self.fake_images, feed_dict={self.z: z_sample})

        save_images(samples[:image_frame_dim * image_frame_dim, :, :, :], [image_frame_dim, image_frame_dim],
                    check_folder(self.result_dir + '/' + self.model_dir) + '/' + self.model_name +
                    '_epoch%03d' % epoch + '_test_all_classes.png')

    @property
    #加载创建固定模型下的路径，本处为GAN下的训练
    def model_dir(self):
        return "{}_{}_{}_{}".format(
            self.model_name, self.dataset_name,
            self.batch_size, self.z_dim)

    #本函数的目的是在于保存训练模型后的checkpoint
    def save(self, checkpoint_dir, step):
        checkpoint_dir = os.path.join(checkpoint_dir, self.model_dir, self.model_name)

        if not os.path.exists(checkpoint_dir):
            os.makedirs(checkpoint_dir)

        self.saver.save(self.sess,os.path.join(checkpoint_dir, self.model_name+'.model'), global_step=step)

    #本函数的意义在于读取训练好的模型参数的checkpoint
    def load(self, checkpoint_dir):
        import re
        print(" [*] Reading checkpoints...")
        checkpoint_dir = os.path.join(checkpoint_dir, self.model_dir, self.model_name)

        ckpt = tf.train.get_checkpoint_state(checkpoint_dir)
        if ckpt and ckpt.model_checkpoint_path:
            ckpt_name = os.path.basename(ckpt.model_checkpoint_path)
            self.saver.restore(self.sess, os.path.join(checkpoint_dir, ckpt_name))
            counter = int(next(re.finditer("(\d+)(?!.*\d)",ckpt_name)).group(0))
            print(" [*] Success to read {}".format(ckpt_name))
            return True, counter
        else:
            print(" [*] Failed to find a checkpoint")
            return False, 0