GAN变种ACGAN利用手写数字识别mnist生成手写数字

1、摘要

本文主要讲解：GAN变种ACGAN利用手写数字识别mnist数据集进行训练，最终生成手写数字图片
主要思路：

Initialize generator and discriminator
Initialize weights
Configure data loader
Optimizers Adam
Train Generator
Train Discriminator
Saves a grid of generated digits ranging from 0 to 9

2、数据介绍

mnist手写数字识别数据集

MNIST数据集由Yann LeCun搜集，是一个大型的手写体数字数据库，通常用于训练各种图像处理系统，也被广泛用于机器学习领域的训练和测试。MNIST数字文字识别数据集数据量不会太多，而且是单色的图像，较简单，适合深度学习初学者练习建立模型、训练、预测。MNIST数据库中的图像集是NIST（National Institute of Standards and Technology）的两个数据库的组合：专用数据库1和特殊数据库3。数据集是有250人手写数字组成，一半是高中生，一半是美国人口普查局。

3、相关技术

本文主要使用pytorch实现ACGAN
pytorch在GitHub上的星星多余tensorflow了，tensorflow升级到2.0版导致以前的很多优秀库不兼容，这是硬伤

ACGAN是在CGAN基础上的进一步拓展，采用辅助分类器（Auxiliary Classifier）使得GAN获取的图像分类的功能。

CGAN通过结合标签信息来提高生成数据的质量，SGAN通过重建标签信息来提高生成数据的质量，那么我们可不可以两者都用，答案是显然的，因为ACGAN就是这样干的。更加详细的内容可以参见论文：Conditional Image Synthesis with Auxiliary Classifier GANs
————————————————
版权声明：本文为CSDN博主「时光碎了天」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：ACGAN 简介与代码实战

4、完整代码和步骤

ACGAN代码在4400个回合生成的手写数字如下：

主运行程序入口

import argparse
import osimport numpy as np
import torch
import torch.nn as nn
import torchvision.transforms as transforms
from torch.autograd import Variable
from torch.utils.data import DataLoader
from torchvision import datasets
from torchvision.utils import save_imageos.makedirs("images", exist_ok=True)parser = argparse.ArgumentParser()
parser.add_argument("--n_epochs", type=int, default=200, help="number of epochs of training")
parser.add_argument("--batch_size", type=int, default=64, help="size of the batches")
parser.add_argument("--lr", type=float, default=0.0002, help="adam: learning rate")
parser.add_argument("--b1", type=float, default=0.5, help="adam: decay of first order momentum of gradient")
parser.add_argument("--b2", type=float, default=0.999, help="adam: decay of first order momentum of gradient")
parser.add_argument("--n_cpu", type=int, default=8, help="number of cpu threads to use during batch generation")
parser.add_argument("--latent_dim", type=int, default=100, help="dimensionality of the latent space")
parser.add_argument("--n_classes", type=int, default=10, help="number of classes for dataset")
parser.add_argument("--img_size", type=int, default=32, help="size of each image dimension")
parser.add_argument("--channels", type=int, default=1, help="number of image channels")
parser.add_argument("--sample_interval", type=int, default=400, help="interval between image sampling")
opt = parser.parse_args()
print(opt)cuda = True if torch.cuda.is_available() else Falsedef weights_init_normal(m):classname = m.__class__.__name__if classname.find("Conv") != -1:torch.nn.init.normal_(m.weight.data, 0.0, 0.02)elif classname.find("BatchNorm2d") != -1:torch.nn.init.normal_(m.weight.data, 1.0, 0.02)torch.nn.init.constant_(m.bias.data, 0.0)class Generator(nn.Module):def __init__(self):super(Generator, self).__init__()self.label_emb = nn.Embedding(opt.n_classes, opt.latent_dim)self.init_size = opt.img_size // 4  # Initial size before upsamplingself.l1 = nn.Sequential(nn.Linear(opt.latent_dim, 128 * self.init_size ** 2))self.conv_blocks = nn.Sequential(nn.BatchNorm2d(128),nn.Upsample(scale_factor=2),nn.Conv2d(128, 128, 3, stride=1, padding=1),nn.BatchNorm2d(128, 0.8),nn.LeakyReLU(0.2, inplace=True),nn.Upsample(scale_factor=2),nn.Conv2d(128, 64, 3, stride=1, padding=1),nn.BatchNorm2d(64, 0.8),nn.LeakyReLU(0.2, inplace=True),nn.Conv2d(64, opt.channels, 3, stride=1, padding=1),nn.Tanh(),)def forward(self, noise, labels):gen_input = torch.mul(self.label_emb(labels), noise)out = self.l1(gen_input)out = out.view(out.shape[0], 128, self.init_size, self.init_size)img = self.conv_blocks(out)return imgclass Discriminator(nn.Module):def __init__(self):super(Discriminator, self).__init__()def discriminator_block(in_filters, out_filters, bn=True):"""Returns layers of each discriminator block"""block = [nn.Conv2d(in_filters, out_filters, 3, 2, 1), nn.LeakyReLU(0.2, inplace=True), nn.Dropout2d(0.25)]if bn:block.append(nn.BatchNorm2d(out_filters, 0.8))return blockself.conv_blocks = nn.Sequential(*discriminator_block(opt.channels, 16, bn=False),*discriminator_block(16, 32),*discriminator_block(32, 64),*discriminator_block(64, 128),)# The height and width of downsampled imageds_size = opt.img_size // 2 ** 4# Output layersself.adv_layer = nn.Sequential(nn.Linear(128 * ds_size ** 2, 1), nn.Sigmoid())self.aux_layer = nn.Sequential(nn.Linear(128 * ds_size ** 2, opt.n_classes), nn.Softmax())def forward(self, img):out = self.conv_blocks(img)out = out.view(out.shape[0], -1)validity = self.adv_layer(out)label = self.aux_layer(out)return validity, label# Loss functions
adversarial_loss = torch.nn.BCELoss()
auxiliary_loss = torch.nn.CrossEntropyLoss()# Initialize generator and discriminator
generator = Generator()
discriminator = Discriminator()if cuda:generator.cuda()discriminator.cuda()adversarial_loss.cuda()auxiliary_loss.cuda()# Initialize weights
generator.apply(weights_init_normal)
discriminator.apply(weights_init_normal)# Configure data loader
os.makedirs("../../data/mnist", exist_ok=True)
dataloader = torch.utils.data.DataLoader(datasets.MNIST("../../data/mnist",train=True,download=True,transform=transforms.Compose([transforms.Resize(opt.img_size), transforms.ToTensor(), transforms.Normalize([0.5], [0.5])]),),batch_size=opt.batch_size,shuffle=True,
)# Optimizers
optimizer_G = torch.optim.Adam(generator.parameters(), lr=opt.lr, betas=(opt.b1, opt.b2))
optimizer_D = torch.optim.Adam(discriminator.parameters(), lr=opt.lr, betas=(opt.b1, opt.b2))FloatTensor = torch.cuda.FloatTensor if cuda else torch.FloatTensor
LongTensor = torch.cuda.LongTensor if cuda else torch.LongTensordef sample_image(n_row, batches_done):"""Saves a grid of generated digits ranging from 0 to n_classes"""# Sample noisez = Variable(FloatTensor(np.random.normal(0, 1, (n_row ** 2, opt.latent_dim))))# Get labels ranging from 0 to n_classes for n rowslabels = np.array([num for _ in range(n_row) for num in range(n_row)])labels = Variable(LongTensor(labels))gen_imgs = generator(z, labels)save_image(gen_imgs.data, "images/%d.png" % batches_done, nrow=n_row, normalize=True)for epoch in range(opt.n_epochs):for i, (imgs, labels) in enumerate(dataloader):batch_size = imgs.shape[0]# Adversarial ground truthsvalid = Variable(FloatTensor(batch_size, 1).fill_(1.0), requires_grad=False)fake = Variable(FloatTensor(batch_size, 1).fill_(0.0), requires_grad=False)# Configure inputreal_imgs = Variable(imgs.type(FloatTensor))labels = Variable(labels.type(LongTensor))# -----------------#  Train Generator# -----------------optimizer_G.zero_grad()# Sample noise and labels as generator inputz = Variable(FloatTensor(np.random.normal(0, 1, (batch_size, opt.latent_dim))))gen_labels = Variable(LongTensor(np.random.randint(0, opt.n_classes, batch_size)))# Generate a batch of imagesgen_imgs = generator(z, gen_labels)# Loss measures generator's ability to fool the discriminatorvalidity, pred_label = discriminator(gen_imgs)g_loss = 0.5 * (adversarial_loss(validity, valid) + auxiliary_loss(pred_label, gen_labels))g_loss.backward()optimizer_G.step()# ---------------------#  Train Discriminator# ---------------------optimizer_D.zero_grad()# Loss for real imagesreal_pred, real_aux = discriminator(real_imgs)d_real_loss = (adversarial_loss(real_pred, valid) + auxiliary_loss(real_aux, labels)) / 2# Loss for fake imagesfake_pred, fake_aux = discriminator(gen_imgs.detach())d_fake_loss = (adversarial_loss(fake_pred, fake) + auxiliary_loss(fake_aux, gen_labels)) / 2# Total discriminator lossd_loss = (d_real_loss + d_fake_loss) / 2# Calculate discriminator accuracypred = np.concatenate([real_aux.data.cpu().numpy(), fake_aux.data.cpu().numpy()], axis=0)gt = np.concatenate([labels.data.cpu().numpy(), gen_labels.data.cpu().numpy()], axis=0)d_acc = np.mean(np.argmax(pred, axis=1) == gt)d_loss.backward()optimizer_D.step()print("[Epoch %d/%d] [Batch %d/%d] [D loss: %f, acc: %d%%] [G loss: %f]"% (epoch, opt.n_epochs, i, len(dataloader), d_loss.item(), 100 * d_acc, g_loss.item()))batches_done = epoch * len(dataloader) + iif batches_done % opt.sample_interval == 0:sample_image(n_row=10, batches_done=batches_done)

5、学习链接

既能生成图像又能进行分类的ACGAN