repvggblock代码python

以下是RepVGG Block的Python代码实现：

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

class RepVGGBlock(nn.Module):
    def __init__(self, in_channels, out_channels, kernel_size=3, stride=1, padding=1, dilation=1, groups=1, deploy=False):
        super(RepVGGBlock, self).__init__()
        self.kernel_size = kernel_size
        self.stride = stride
        self.padding = padding
        self.dilation = dilation
        self.groups = groups
        self.deploy = deploy
        
        self.conv = nn.Conv2d(in_channels, out_channels, kernel_size, stride, padding, dilation, groups, bias=False)
        self.bn = nn.BatchNorm2d(out_channels)
        self.relu = nn.ReLU(inplace=True)
        if deploy:
            self.rbr_reparam = nn.Conv2d(out_channels, out_channels, kernel_size, stride, padding, dilation, groups, bias=True)
        
    def forward(self, x):
        if not self.deploy:
            x = self.conv(x)
            x = self.bn(x)
            x = self.relu(x)
        else:
            weight = self.conv.weight
            bias = self.conv.bias
            rbr_weight, rbr_bias = self._get_reparam_weight_bias(weight, bias)
            x = F.conv2d(x, rbr_weight, rbr_bias, self.stride, self.padding, self.dilation, self.groups)
        return x
    
    def _get_reparam_weight_bias(self, weight, bias):
        kernel_size = self.kernel_size
        stride = self.stride
        padding = self.padding
        dilation = self.dilation
        groups = self.groups
        assert kernel_size == 3 and stride == 1
        assert padding == 1 or padding == (1, 1)
        assert dilation == 1 and groups == 1
        assert weight.shape[2] == kernel_size and weight.shape[3] == kernel_size
        assert isinstance(self.bn, nn.BatchNorm2d)
        gamma = self.bn.weight
        beta = self.bn.bias
        mean = self.bn.running_mean
        var = self.bn.running_var
        eps = self.bn.eps
        std = (var + eps).sqrt()
        t = weight.transpose(0, 1) / std.reshape(-1, 1, 1, 1)
        t = t.reshape(weight.shape[1], -1)
        U, S, V = torch.svd(t)
        U = U[:, :kernel_size]
        V = V[:, :kernel_size]
        S = S[:kernel_size]
        d = torch.sign(torch.diag(V))
        U *= d
        V *= d
        rbr_weight = (V @ U.transpose(0, 1)).reshape(weight.shape)
        rbr_bias = beta - gamma * mean / std
        rbr_bias = (V @ S @ U.transpose(0, 1) @ rbr_bias.reshape(-1, 1)).reshape(-1) + bias
        return rbr_weight, rbr_bias

这里实现了RepVGG Block的前向传播方法 forward() 和获取重参数化权重和偏置的方法 _get_reparam_weight_bias()。RepVGG Block 可以根据 deploy 参数选择是否使用重参数化技术。如果 deploy 参数为 False，则使用普通的卷积、批归一化和 ReLU 激活函数；如果 deploy 参数为 True，则使用重参数化后的卷积和带有偏置的 ReLU 激活函数。