ResNet(残差网络)是一种深度神经网络的结构,它通过残差块(Residual block)的堆叠来训练非常深的网络。下面是使用PyTorch
实现 ResNet18的
代码示例:
import torch.nn as nnimport torch.nn.functional as Fclass ResidualBlock(nn.Module):def __init__(self, in_channels, out_channels, stride=1):super(ResidualBlock, self).__init__()self.conv1 = nn.Conv2d(in_channels, out_channels, kernel_size=3, stride=stride, padding=1, bias=False)self.bn1 = nn.BatchNorm2d(out_channels)self.conv2 = nn.Conv2d(out_channels, out_channels, kernel_size=3, stride=1, padding=1, bias=False)self.bn2 = nn.BatchNorm2d(out_channels)self.shortcut = nn.Sequential()if stride != 1 or in_channels != out_channels:self.shortcut = nn.Sequential(nn.Conv2d(in_channels, out_channels, kernel_size=1, stride=stride, bias=False),nn.BatchNorm2d(out_channels))def forward(self, x):residual = xout = F.relu(self.bn1(self.conv1(x)))out = self.bn2(self.conv2(out))out += self.shortcut(residual)out = F.relu(out)return outclassResNet(nn.Module):def __init__(self, block, num_blocks, num_classes=10):super(ResNet, self).__init__()self.in_channels = 64self.conv1 = nn.Conv2d(3, 64, kernel_size=3, stride=1, padding=1, bias=False)self.bn1 = nn.BatchNorm2d(64)self.layer1 = self.make_layer(block, 64, num_blocks[0], stride=1)self.layer2 = self.make_layer(block, 128, num_blocks[1], stride=2)self.layer3 = self.make_layer(block, 256, num_blocks[2], stride=2)self.layer4 = self.make_layer(block, 512, num_blocks[3], stride=2)self.avg_pool = nn.AdaptiveAvgPool2d((1, 1))self.fc = nn.Linear(512, num_classes)def make_layer(self, block, out_channels, num_blocks, stride):strides = [stride] + [1] * (num_blocks - 1)layers = []for stride in strides:layers.append(block(self.in_channels, out_channels, stride))self.in_channels = out_channelsreturn nn.Sequential(*layers)def forward(self, x):out = F.relu(self.bn1(self.conv1(x)))out = self.layer1(out)out = self.layer2(out)out = self.layer3(out)out = self.layer4(out)out = self.avg_pool(out)out = out.view(out.size(0), -1)out = self.fc(out)return outdefresnet18():returnResNet(ResidualBlock, [2, 2, 2, 2])
在上面的
代码中,我们首先定义了残差块`ResidualBlock`,然后定义了主要的
ResNet模型`
ResNet`。需要注意的是,`
ResNet`中包含了4个残差块的堆叠,每个残差块中又包含了2个卷积层,因此我们需要定义一个用于生成残差块的函数`make_layer`。最后,我们定义了一个`
resnet18`函数,用于生成
ResNet18模型。
今天的文章 2025年resnet50网络结构代码(resnet152网络结构)分享到此就结束了,感谢您的阅读。
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