resnet18+交叉注意力机制代码

以下是使用ResNet18和交叉注意力机制的PyTorch代码示例：

import torch
import torch.nn as nn
import torch.nn.functional as F

class CrossAttentionModule(nn.Module):
    def __init__(self, in_channels):
        super(CrossAttentionModule, self).__init__()
        self.query_conv = nn.Conv2d(in_channels, in_channels // 8, kernel_size=1)
        self.key_conv = nn.Conv2d(in_channels, in_channels // 8, kernel_size=1)
        self.value_conv = nn.Conv2d(in_channels, in_channels, kernel_size=1)
        self.gamma = nn.Parameter(torch.zeros(1))
        self.softmax = nn.Softmax(dim=-1)

    def forward(self, x):
        batch_size, channels, height, width = x.size()
        proj_query = self.query_conv(x).view(batch_size, -1, width * height).permute(0, 2, 1)
        proj_key = self.key_conv(x).view(batch_size, -1, width * height)
        energy = torch.bmm(proj_query, proj_key)
        attention = self.softmax(energy)
        proj_value = self.value_conv(x).view(batch_size, -1, width * height)
        out = torch.bmm(proj_value, attention.permute(0, 2, 1))
        out = out.view(batch_size, channels, height, width)
        out = self.gamma * out + x
        return out

class ResNet18(nn.Module):
    def __init__(self, num_classes=1000):
        super(ResNet18, self).__init__()
        self.conv1 = nn.Conv2d(3, 64, kernel_size=7, stride=2, padding=3, bias=False)
        self.bn1 = nn.BatchNorm2d(64)
        self.relu = nn.ReLU(inplace=True)
        self.maxpool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1)
        self.layer1 = nn.Sequential(
            nn.Conv2d(64, 64, kernel_size=3, stride=1, padding=1, bias=False),
            nn.BatchNorm2d(64),
            nn.ReLU(inplace=True),
            nn.Conv2d(64, 64, kernel_size=3, stride=1, padding=1, bias=False),
            nn.BatchNorm2d(64),
            CrossAttentionModule(64),
            nn.ReLU(inplace=True)
        )
        self.layer2 = nn.Sequential(
            nn.Conv2d(64, 128, kernel_size=3, stride=2, padding=1, bias=False),
            nn.BatchNorm2d(128),
            nn.ReLU(inplace=True),
            nn.Conv2d(128, 128, kernel_size=3, stride=1, padding=1, bias=False),
            nn.BatchNorm2d(128),
            CrossAttentionModule(128),
            nn.ReLU(inplace=True)
        )
        self.layer3 = nn.Sequential(
            nn.Conv2d(128, 256, kernel_size=3, stride=2, padding=1, bias=False),
            nn.BatchNorm2d(256),
            nn.ReLU(inplace=True),
            nn.Conv2d(256, 256, kernel_size=3, stride=1, padding=1, bias=False),
            nn.BatchNorm2d(256),
            CrossAttentionModule(256),
            nn.ReLU(inplace=True)
        )
        self.layer4 = nn.Sequential(
            nn.Conv2d(256, 512, kernel_size=3, stride=2, padding=1, bias=False),
            nn.BatchNorm2d(512),
            nn.ReLU(inplace=True),
            nn.Conv2d(512, 512, kernel_size=3, stride=1, padding=1, bias=False),
            nn.BatchNorm2d(512),
            CrossAttentionModule(512),
            nn.ReLU(inplace=True)
        )
        self.avgpool = nn.AdaptiveAvgPool2d((1, 1))
        self.fc = nn.Linear(512, num_classes)

    def forward(self, x):
        x = self.conv1(x)
        x = self.bn1(x)
        x = self.relu(x)
        x = self.maxpool(x)

        x = self.layer1(x)
        x = self.layer2(x)
        x = self.layer3(x)
        x = self.layer4(x)

        x = self.avgpool(x)
        x = x.view(x.size(0), -1)
        x = self.fc(x)
        return x

这个模型定义了一个ResNet18网络，并使用了交叉注意力机制来增强特征表示。在ResNet18的每个残差块之后，我们添加了一个CrossAttentionModule层。这个层包括一个查询卷积、一个键卷积和一个值卷积，这些卷积用于计算注意力，然后将注意力应用于特征图。注意力通过对查询和键之间的点积进行softmax计算得到。注意力加权的值特征图与原始特征图相加，得到增强的特征表示。