使用压缩自编码实现手写数字识别

import os
import argparse
import torch
import torch.utils.data
import torch.nn as nn
import torch.optim as optim
from torch.autograd import Variable
from torchvision import datasets, transforms
# import pdb
import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
import matplotlib.gridspec as gridspec

os.environ["CUDA_DEVICE_ORDER"]="PCI_BUS_ID"   # see issue #152
os.environ["CUDA_VISIBLE_DEVICES"]="1"

os.environ["KMP_DUPLICATE_LIB_OK"]="TRUE"

print("Imported all libraries successfully!")

parser = argparse.ArgumentParser(description='PyTorch MNIST Example for CAE')
parser.add_argument('--batch-size', type=int, default=128, metavar='N',
                    help='input batch size for training (default: 64)')
parser.add_argument('--epochs', type=int, default=100, metavar='N',
                    help='number of epochs to train (default: 2)')
parser.add_argument('--no-cuda', action='store_true', default=False,
                    help='enables CUDA training')
parser.add_argument('--seed', type=int, default=1, metavar='S',
                    help='random seed (default: 1)')
parser.add_argument('--log-interval', type=int, default=10, metavar='N',
                    help='how many batches to wait before logging training status')
args = parser.parse_args()
args.cuda = not args.no_cuda and torch.cuda.is_available()

torch.manual_seed(args.seed)
if args.cuda:
    torch.cuda.manual_seed(args.seed)

kwargs = {'num_workers': 5, 'pin_memory': True} if args.cuda else {}

Download_Minst = False # 已经下载过了设置为false

# 判断数据是否下载
if not(os.path.exists('data')) or not os.listdir('data'):
    Download_Minst = True  

# 下载数据
train_loader = torch.utils.data.DataLoader(
	datasets.MNIST('data', train=True, download=True,
		transform=transforms.ToTensor()),
	batch_size=args.batch_size, shuffle=True, **kwargs)

test_loader = torch.utils.data.DataLoader(
    datasets.MNIST('data', train=False, transform=transforms.ToTensor()),
    batch_size=args.batch_size, shuffle=True, **kwargs)

lam = 1e-4

# 创建网络构架
class CAE(nn.Module):
	def __init__(self):
		super(CAE, self).__init__()

		self.fc1 = nn.Linear(784, 400, bias = False) # Encoder
		self.fc2 = nn.Linear(400, 784, bias = False) # Decoder

		self.relu = nn.ReLU()
		self.sigmoid = nn.Sigmoid()

	def encoder(self, x):
		h1 = self.relu(self.fc1(x.view(-1, 784)))
		return h1

	def decoder(self,z):
		h2 = self.sigmoid(self.fc2(z))
		return h2

	def forward(self, x):
            h1 = self.encoder(x)
            h2 = self.decoder(h1)
            return h1, h2

        # Writing data in a grid to check the quality and progress
	def samples_write(self, x, epoch):
		_, samples = self.forward(x)
		#pdb.set_trace()
		samples = samples.data.cpu().numpy()[:16]
		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')
		if not os.path.exists('out/'):
			os.makedirs('out/')
		plt.savefig('out/{}.png'.format(str(epoch).zfill(3)), bbox_inches='tight')
		#self.c += 1
		plt.close(fig)


mse_loss = nn.BCELoss(size_average = False)

def loss_function(W, x, recons_x, h, lam):
    mse = mse_loss(recons_x, x)
    # Since: W is shape of N_hidden x N. So, we do not need to transpose it as
    # opposed to #1
    dh = h * (1 - h) # Hadamard product produces size N_batch x N_hidden
    # Sum through the input dimension to improve efficiency, as suggested in #1
    w_sum = torch.sum(Variable(W)**2, dim=1)
    # unsqueeze to avoid issues with torch.mv
    w_sum = w_sum.unsqueeze(1) # shape N_hidden x 1
    contractive_loss = torch.sum(torch.mm(dh**2, w_sum), 0)
    return mse + contractive_loss.mul_(lam)


model = CAE()
optimizer = optim.Adam(model.parameters(), lr = 0.0001)

if args.cuda:
    model.cuda()

def train(epoch):
    model.train()
    train_loss = 0

    for idx, (data, _) in enumerate(train_loader):
        data = Variable(data)
        if args.cuda:
            data = data.cuda()

        optimizer.zero_grad()

        hidden_representation, recons_x = model(data)

        # Get the weights
        # model.state_dict().keys()
        # change the key by seeing the keys manually.
        # (In future I will try to make it automatic)
        W = model.state_dict()['fc1.weight']
        loss = loss_function(W, data.view(-1, 784), recons_x,
                             hidden_representation, lam)

        loss.backward()
        train_loss += loss.data[0]
        optimizer.step()

        if idx % args.log_interval == 0:
            print('Train epoch: {} [{}/{}({:.0f}%)]\t Loss: {:.6f}'.format(
                  epoch, idx*len(data), len(train_loader.dataset),
                  100*idx/len(train_loader),
                  loss.data[0]/len(data)))


    print('====> Epoch: {} Average loss: {:.4f}'.format(
         epoch, train_loss / len(train_loader.dataset)))
    model.samples_write(data,epoch)

for epoch in range(args.epochs):
    train(epoch)

部分结果：