self.avgpool = nn.AdaptiveAvgPool3d((1, 1, 1))

这段代码是一个 PyTorch 中的 3D 自适应平均池化层，它将输入的 3D 张量在空间维度上进行平均池化，并输出一个形状为 (batch_size, num_channels, 1, 1, 1) 的张量。这个层通常用于将任意大小的 3D 输入张量压缩成一个固定大小的特征向量，以便用于分类或其他任务。

相关问题

定义ResNet18模型 class ResNet18(nn.Module): def init(self): super(ResNet18, self).init() self.conv1 = nn.Conv2d(3, 64, kernel_size=3, stride=1, padding=1, bias=False) self.bn1 = nn.BatchNorm2d(64) self.relu = nn.ReLU(inplace=True) 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) ) 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), ) 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), ) 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), ) self.avgpool = nn.AdaptiveAvgPool2d((1, 1)) self.fc = nn.Linear(512, 10) def forward(self, x): x = self.conv1(x) x = self.bn1(x) x = self.relu(x) x = self.layer1(x) + x x = self.layer2(x) + x x = self.layer3(x) + x x = self.layer4(x) + x x = self.avgpool(x) x = x.view(x.size(0), -1) x = self.fc(x) return x

这段代码定义了一个名为 ResNet18 的模型，它是一个继承自 nn.Module 的子类。让我逐行解读这些代码：

class ResNet18(nn.Module):
    def __init__(self):
        super(ResNet18, self).__init__()
        self.conv1 = nn.Conv2d(3, 64, kernel_size=3, stride=1, padding=1, bias=False)
        self.bn1 = nn.BatchNorm2d(64)
        self.relu = nn.ReLU(inplace=True)
        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)
        )
        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),
        )
        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),
        )
        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),
        )
        self.avgpool = nn.AdaptiveAvgPool2d((1, 1))
        self.fc = nn.Linear(512, 10)

- `ResNet18(nn.Module)`：定义了一个名为 ResNet18 的类，它继承自 nn.Module。
- `def __init__(self):`：定义类的初始化方法。
- `super(ResNet18, self).__init__()`：调用父类的初始化方法，确保父类的属性被正确初始化。
- `self.conv1 = nn.Conv2d(3, 64, kernel_size=3, stride=1, padding=1, bias=False)`：定义了一个卷积层，输入通道数为3（RGB图像），输出通道数为64，卷积核大小为3x3，步长为1，填充为1，不使用偏置。
- `self.bn1 = nn.BatchNorm2d(64)`：定义了一个批归一化层，对输入的64个通道进行归一化。
- `self.relu = nn.ReLU(inplace=True)`：定义了一个 ReLU 激活函数，inplace=True 表示原地操作，节省内存。
- `self.layer1`、`self.layer2`、`self.layer3`、`self.layer4`：定义了4个残差块，每个残差块包含一系列的卷积层和批归一化层。
- `self.avgpool = nn.AdaptiveAvgPool2d((1, 1))`：定义了一个自适应平均池化层，将输入的特征图大小自适应地池化为大小为1x1。
- `self.fc = nn.Linear(512, 10)`：定义了一个全连接层，将输入特征的维度从512降至10。

def forward(self, x):
    x = self.conv1(x)
    x = self.bn1(x)
    x = self.relu(x)
    x = self.layer1(x) + x
    x = self.layer2(x) + x
    x = self.layer3(x) + x
    x = self.layer4(x) + x
    x = self.avgpool(x)
    x = x.view(x.size(0), -1)
    x = self.fc(x)
    return x

- `def forward(self, x):`：定义了前向传播的方法。
- `x = self.conv1(x)`：将输入 `x` 通过卷积层 `self.conv1` 进行卷积操作。
- `x = self.bn1(x)`：将卷积后的结果 `x` 通过批归一化层 `self.bn1` 进行归一化。
- `x = self.relu(x)`：将归一化后的结果 `x` 通过 ReLU 激活函数进行激活。
- `x = self.layer1(x) + x`：将 `x` 与 `self.layer1(x)` 相加，实现残差连接。
- `x = self.layer2(x) + x`、`x = self.layer3(x) + x`、`x = self.layer4(x) + x`：依次将 `x` 与 `self.layer2(x)`、`self.layer3(x)`、`self.layer4(x)` 相加，实现残差连接。
- `x = self.avgpool(x)`：将输入 `x` 通过自适应平均池化层 `self.avgpool` 进行池化操作。
- `x = x.view(x.size(0), -1)`：将池化后的结果 `x` 展平成一维向量。
- `x = self.fc(x)`：将展平后的结果 `x` 通过全连接层 `self.fc` 进行线性变换。
- `return x`：返回前向传播的结果。

这段代码定义了一个包含卷积层、批归一化层、残差块和全连接层的 ResNet18 模型，并实现了前向传播方法。

更改import torch import torchvision.models as models import torch.nn as nn import torch.nn.functional as F class eca_Resnet50(nn.Module): def init(self): super().init() self.model = models.resnet50(pretrained=True) self.model.avgpool = nn.AdaptiveAvgPool2d((1,1)) self.model.fc = nn.Linear(2048, 1000) self.eca = ECA_Module(2048, 8) def forward(self, x): x = self.model.conv1(x) x = self.model.bn1(x) x = self.model.relu(x) x = self.model.maxpool(x) x = self.model.layer1(x) x = self.model.layer2(x) x = self.model.layer3(x) x = self.model.layer4(x) x = self.eca(x) x = self.model.avgpool(x) x = torch.flatten(x, 1) x = self.model.fc(x) return x class ECA_Module(nn.Module): def init(self, channel, k_size=3): super(ECA_Module, self).init() self.avg_pool = nn.AdaptiveAvgPool2d(1) self.conv = nn.Conv1d(1, 1, kernel_size=k_size, padding=(k_size - 1) // 2, bias=False) self.sigmoid = nn.Sigmoid() def forward(self, x): b, c, _, _ = x.size() y = self.avg_pool(x) y = self.conv(y.squeeze(-1).transpose(-1,-2)).transpose(-1,-2).unsqueeze(-1) y = self.sigmoid(y) return x * y.expand_as(x) class ImageDenoising(nn.Module): def init(self): super().init() self.model = eca_Resnet50() self.conv1 = nn.Conv2d(3, 64, kernel_size=3, stride=1, padding=1) self.conv2 = nn.Conv2d(64, 64, kernel_size=3, stride=1, padding=1) self.conv3 = nn.Conv2d(64, 3, kernel_size=3, stride=1, padding=1) def forward(self, x): x = self.conv1(x) x = F.relu(x) x = self.conv2(x) x = F.relu(x) x = self.conv3(x) x = F.relu(x) return x，使最后输出为[16,1,50,50,]。

更改后的代码如下：

import torch
import torchvision.models as models
import torch.nn as nn
import torch.nn.functional as F

class eca_Resnet50(nn.Module):
    def __init__(self):
        super().__init__()
        self.model = models.resnet50(pretrained=True)
        self.model.avgpool = nn.AdaptiveAvgPool2d((1,1))
        self.model.fc = nn.Linear(2048, 1000)
        self.eca = ECA_Module(2048, 8)

    def forward(self, x):
        x = self.model.conv1(x)
        x = self.model.bn1(x)
        x = self.model.relu(x)
        x = self.model.maxpool(x)
        x = self.model.layer1(x)
        x = self.model.layer2(x)
        x = self.model.layer3(x)
        x = self.model.layer4(x)
        x = self.eca(x)
        x = self.model.avgpool(x)
        x = torch.flatten(x, 1)
        x = self.model.fc(x)
        return x

class ECA_Module(nn.Module):
    def __init__(self, channel, k_size=3):
        super().__init__()
        self.avg_pool = nn.AdaptiveAvgPool2d(1)
        self.conv = nn.Conv1d(1, 1, kernel_size=k_size, padding=(k_size - 1) // 2, bias=False)
        self.sigmoid = nn.Sigmoid()

    def forward(self, x):
        b, c, _, _ = x.size()
        y = self.avg_pool(x)
        y = self.conv(y.squeeze(-1).transpose(-1,-2)).transpose(-1,-2).unsqueeze(-1)
        y = self.sigmoid(y)
        return x * y.expand_as(x)

class ImageDenoising(nn.Module):
    def __init__(self):
        super().__init__()
        self.model = eca_Resnet50()
        self.conv1 = nn.Conv2d(3, 64, kernel_size=3, stride=1, padding=1)
        self.conv2 = nn.Conv2d(64, 64, kernel_size=3, stride=1, padding=1)
        self.conv3 = nn.Conv2d(64, 1, kernel_size=3, stride=1, padding=1)

    def forward(self, x):
        x = self.conv1(x)
        x = F.relu(x)
        x = self.conv2(x)
        x = F.relu(x)
        x = self.conv3(x)
        x = F.relu(x)
        x = x.view(-1, 1, 50, 50)
        return x

在修改的过程中，主要是将最后一层卷积层的输出通道数改为 1，并在 forward 方法中添加了 x.view(-1, 1, 50, 50)，将输出的大小修改为 [16,1,50,50]。