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import time import torch from torch import nn, optim import torchvision import sys sys.path.append("..") import d2lzh_pytorch as d2l device = torch.device('cuda' if torch.cuda.is_available() else 'cpu') class AlexNet(nn.Module): def __init__(self): super(AlexNet, self).__init__() self.conv = nn.Sequential( nn.Conv2d(1, 96, 11, 4), # in_channels, out_channels, kernel_size, stride, padding nn.ReLU(), nn.MaxPool2d(3, 2), # kernel_size, stride # 减小卷积窗口,使用填充为2来使得输入与输出的高和宽一致,且增大输出通道数 nn.Conv2d(96, 256, 5, 1, 2), nn.ReLU(), nn.MaxPool2d(3, 2), # 连续3个卷积层,且使用更小的卷积窗口。除了最后的卷积层外,进一步增大了输出通道数。 # 前两个卷积层后不使用池化层来减小输入的高和宽 nn.Conv2d(256, 384, 3, 1, 1), nn.ReLU(), nn.Conv2d(384, 384, 3, 1, 1), nn.ReLU(), nn.Conv2d(384, 256, 3, 1, 1), nn.ReLU(), nn.MaxPool2d(3, 2) ) # 这里全连接层的输出个数比LeNet中的大数倍。使用丢弃层来缓解过拟合 self.fc = nn.Sequential( nn.Linear(256*5*5, 4096), nn.ReLU(), nn.Dropout(0.5), nn.Linear(4096, 4096), nn.ReLU(), nn.Dropout(0.5), # 输出层。由于这里使用Fashion-MNIST,所以用类别数为10,而非论文中的1000 nn.Linear(4096, 10), ) def forward(self, img): feature = self.conv(img) output = self.fc(feature.view(img.shape[0], -1)) return output net = AlexNet() print(net) batch_size = 1 # 如出现“out of memory”的报错信息,可减小batch_size或resize train_iter, test_iter = d2l.load_data_fashion_mnist(batch_size, resize=224) lr, num_epochs = 0.001, 5 optimizer = torch.optim.Adam(net.parameters(), lr=lr) d2l.train_ch5(net, train_iter, test_iter, batch_size, optimizer, device, num_epochs)
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