main_linear.py

import torch
import torch.nn as nn
import torch.nn.functional as F
import torch.optim as optim
from torchvision import datasets, transforms
from torch.autograd import Variable
from torchvision.utils import save_image
import numpy as np
from matplotlib import pyplot as plt

# Ref: https://github.com/lyeoni/pytorch-mnist-VAE/blob/master/pytorch-mnist-VAE.ipynb

class VAE(nn.Module):
    def __init__(self, x_dim, h_dim1, h_dim2, z_dim):
        super(VAE, self).__init__()

        # encoder part
        self.fc1 = nn.Linear(x_dim, h_dim1)
        self.fc2 = nn.Linear(h_dim1, h_dim2)
        self.fc31 = nn.Linear(h_dim2, z_dim)
        self.fc32 = nn.Linear(h_dim2, z_dim)
        # decoder part
        self.fc4 = nn.Linear(z_dim, h_dim2)
        self.fc5 = nn.Linear(h_dim2, h_dim1)
        self.fc6 = nn.Linear(h_dim1, x_dim)

    def encoder(self, x):
        h = F.relu(self.fc1(x))
        h = F.relu(self.fc2(h))
        return self.fc31(h), self.fc32(h)  # mu, log_var

    def sampling(self, mu, log_var):
        std = torch.exp(0.5 * log_var)
        eps = torch.randn_like(std)
        return eps.mul(std).add_(mu)  # return z sample

    def decoder(self, z):
        h = F.relu(self.fc4(z))
        h = F.relu(self.fc5(h))
        return F.sigmoid(self.fc6(h))

    def forward(self, x):
        mu, log_var = self.encoder(x.view(-1, 784))
        z = self.sampling(mu, log_var)
        return self.decoder(z), mu, log_var

def loss_function(recon_x, x, mu, log_var):
    BCE = F.binary_cross_entropy(recon_x, x.view(-1, 784), reduction='sum')
    KLD = -0.5 * torch.sum(1 + log_var - mu.pow(2) - log_var.exp())
    return BCE + KLD


def train(epoch, vae, train_loader, optimizer):
    vae.train()
    train_loss = 0
    for batch_idx, (data, _) in enumerate(train_loader):
        data = data.cuda()
        optimizer.zero_grad()

        recon_batch, mu, log_var = vae(data)
        loss = loss_function(recon_batch, data, mu, log_var)

        loss.backward()
        train_loss += loss.item()
        optimizer.step()

        if batch_idx % 100 == 0:
            print('Train Epoch: {} [{}/{} ({:.0f}%)]\tLoss: {:.6f}'.format(
                epoch, batch_idx * len(data), len(train_loader.dataset),
                       100. * batch_idx / len(train_loader), loss.item() / len(data)))
    print('====> Epoch: {} Average loss: {:.4f}'.format(epoch, train_loss / len(train_loader.dataset)))


def test(vae, test_loader):
    vae.eval()
    test_loss = 0
    with torch.no_grad():
        for data, _ in test_loader:
            data = data.cuda()
            recon, mu, log_var = vae(data)

            # sum up batch loss
            test_loss += loss_function(recon, data, mu, log_var).item()

    test_loss /= len(test_loader.dataset)
    print('====> Test set loss: {:.4f}'.format(test_loss))

def main():

    print('this is hw3')
    device = 'cuda' if torch.cuda.is_available() else 'cpu'
    print(device)

    bs = 100
    # MNIST Dataset
    train_dataset = datasets.MNIST(root='./mnist_data/', train=True, transform=transforms.ToTensor(), download=True)
    test_dataset = datasets.MNIST(root='./mnist_data/', train=False, transform=transforms.ToTensor(), download=False)

    # Data Loader (Input Pipeline)
    train_loader = torch.utils.data.DataLoader(dataset=train_dataset, batch_size=bs, shuffle=True)
    test_loader = torch.utils.data.DataLoader(dataset=test_dataset, batch_size=bs, shuffle=False)

    vae = VAE(x_dim=784, h_dim1=512, h_dim2=256, z_dim=2)
    if torch.cuda.is_available():
        vae.cuda()

    optimizer = optim.Adam(vae.parameters())

    # Training:
    for epoch in range(1, 15):
        train(epoch, vae, train_loader, optimizer)
        test(vae, test_loader)

    with torch.no_grad():
        z = torch.randn(64, 2).cuda()
        sample = vae.decoder(z).cuda()
        save_image(sample.view(64, 1, 28, 28), './samples/sample_' + '.png')

    images, labels = iter(test_loader).next()
    sample_pic = images[0]

    #sample_pic = test_dataset[4]
    plt.imshow(sample_pic[0].reshape(28, 28), cmap="gray")
    plt.show()

    with torch.no_grad():
        sample_pic = sample_pic.cuda()
        result = vae.forward(sample_pic)
        print('Got result')
        result = result[0].cpu()
        plt.imshow(result.reshape(28, 28), cmap="gray")
        plt.show()

if __name__ == '__main__':
    main()