class AffineLayer(nn.Module): def __init__(self, num_channels, bias=False): super(AffineLayer, self).__init__() weight = torch.FloatTensor(1, num_channels, 1, 1).fill_(1) self.weight = nn.Parameter(weight, requires_grad=True) self.bias = None if bias: bias = torch.FloatTensor(1, num_channels, 1, 1).fill_(0) self.bias = nn.Parameter(bias, requires_grad=True) def forward(self, X): out = X * self.weight.expand_as(X) if self.bias is not None: out = out + self.bias.expand_as(X) return out
时间: 2024-04-26 12:21:03 浏览: 60
这是一个 PyTorch 中的仿射层(Affine Layer)的实现,它可以对输入进行线性变换和平移。其中,num_channels 表示输入的通道数,bias 表示是否使用偏置。在初始化时,权重矩阵的元素都被初始化为 1,偏置矩阵的元素被初始化为 0。在前向传播时,对输入进行线性变换后加上偏置(如果有)。最后返回处理后的输出。
相关问题
class GradientDecoupleLayer(Function): @staticmethod def forward(ctx, x, _lambda): ctx._lambda = _lambda return x @staticmethod def backward(ctx, grad_output): grad_output = grad_output * ctx._lambda return grad_output, None class AffineLayer(nn.Module): def __init__(self, num_channels, bias=False): super(AffineLayer, self).__init__() weight = torch.FloatTensor(1, num_channels, 1, 1).fill_(1) self.weight = nn.Parameter(weight, requires_grad=True) self.bias = None if bias: bias = torch.FloatTensor(1, num_channels, 1, 1).fill_(0) self.bias = nn.Parameter(bias, requires_grad=True) def forward(self, X): out = X * self.weight.expand_as(X) if self.bias is not None: out = out + self.bias.expand_as(X) return out def decouple_layer(x, _lambda): return GradientDecoupleLayer.apply(x, _lambda)
这段代码看起来是 PyTorch 的代码,其中定义了两个类:GradientDecoupleLayer 和 AffineLayer。GradientDecoupleLayer 是一个自定义的 PyTorch 函数,实现了一个梯度解耦的功能;AffineLayer 是一个继承自 nn.Module 的类,实现了一个仿射变换的功能。其中,AffineLayer 的实现比较简单,就是将输入 X 乘上一个可学习的权重参数 self.weight,再加上一个可选的偏置参数 self.bias;而 GradientDecoupleLayer 则是比较复杂的一个函数,它的作用是将输入 x 的梯度乘上一个常数 _lambda,然后输出。这个函数的实现用到了 PyTorch 的静态方法 apply,并且在 backward 函数中返回了梯度 grad_output 乘上 _lambda 的结果。
class BasicBlock2D(nn.Module): expansion = 1 def __init__(self, in_channels, out_channels, stride=1): super(BasicBlock2D, 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 != self.expansion * out_channels: self.shortcut = nn.Sequential( nn.Conv2d(in_channels, self.expansion * out_channels, kernel_size=1, stride=stride, bias=False), nn.BatchNorm2d(self.expansion * out_channels) ) def forward(self, x): out = F.relu(self.bn1(self.conv1(x))) out = self.bn2(self.conv2(out)) out += self.shortcut(x) out = F.relu(out) return out # 定义二维ResNet-18模型 class ResNet18_2D(nn.Module): def __init__(self, num_classes=1000): super(ResNet18_2D, self).__init__() self.in_channels = 64 self.conv1 = nn.Conv2d(1, 64, kernel_size=7, stride=2, padding=3, bias=False) self.bn1 = nn.BatchNorm2d(64) self.maxpool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1) self.layer1 = self._make_layer(BasicBlock2D, 64, 2, stride=1) self.layer2 = self._make_layer(BasicBlock2D, 128, 2, stride=2) self.layer3 = self._make_layer(BasicBlock2D, 256, 2, stride=2) self.layer4 = self._make_layer(BasicBlock2D, 512, 2, stride=2) self.avgpool = nn.AdaptiveAvgPool2d((1, 1)) self.fc = nn.Linear(512 , 512) def _make_layer(self, block, out_channels, num_blocks, stride): layers = [] layers.append(block(self.in_channels, out_channels, stride)) self.in_channels = out_channels * block.expansion for _ in range(1, num_blocks): layers.append(block(self.in_channels, out_channels)) return nn.Sequential(*layers) def forward(self, x): out = F.relu(self.bn1(self.conv1(x))) out = self.maxpool(out) out = self.layer1(out) out = self.layer2(out) out = self.layer3(out) out = self.layer4(out) out = self.avgpool(out) # print(out.shape) out = out.view(out.size(0), -1) out = self.fc(out) return out改为用稀疏表示替换全连接层
为了用稀疏表示替换全连接层,需要先将特征图展平,然后使用稀疏矩阵与其进行乘法运算。
以下是修改后的代码:
```
import torch.sparse as sparse
class ResNet18_2D(nn.Module):
def __init__(self, num_classes=1000):
super(ResNet18_2D, self).__init__()
self.in_channels = 64
self.conv1 = nn.Conv2d(1, 64, kernel_size=7, stride=2, padding=3, bias=False)
self.bn1 = nn.BatchNorm2d(64)
self.maxpool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1)
self.layer1 = self._make_layer(BasicBlock2D, 64, 2, stride=1)
self.layer2 = self._make_layer(BasicBlock2D, 128, 2, stride=2)
self.layer3 = self._make_layer(BasicBlock2D, 256, 2, stride=2)
self.layer4 = self._make_layer(BasicBlock2D, 512, 2, stride=2)
self.avgpool = nn.AdaptiveAvgPool2d((1, 1))
# 替换全连接层
self.fc = nn.Identity()
def _make_layer(self, block, out_channels, num_blocks, stride):
layers = []
layers.append(block(self.in_channels, out_channels, stride))
self.in_channels = out_channels * block.expansion
for _ in range(1, num_blocks):
layers.append(block(self.in_channels, out_channels))
return nn.Sequential(*layers)
def forward(self, x):
out = F.relu(self.bn1(self.conv1(x)))
out = self.maxpool(out)
out = self.layer1(out)
out = self.layer2(out)
out = self.layer3(out)
out = self.layer4(out)
out = self.avgpool(out)
out = out.view(out.size(0), -1)
# 使用稀疏矩阵与展平后的特征图进行乘法运算
out = sparse.mm(out, nn.Parameter(torch.randn(out.size(1), 512)))
return out
```