（超详细）8-YOLOV5改进-添加EMA意力机制

1、在yolov5/models下面新建一个EMA.py文件，在里面放入下面的代码
在这里插入图片描述
代码如下：

import torch
from torch import nnclass EMA(nn.Module):def __init__(self, channels, factor=8):super(EMA, self).__init__()self.groups = factorassert channels // self.groups > 0self.softmax = nn.Softmax(-1)self.agp = nn.AdaptiveAvgPool2d((1, 1))self.pool_h = nn.AdaptiveAvgPool2d((None, 1))self.pool_w = nn.AdaptiveAvgPool2d((1, None))self.gn = nn.GroupNorm(channels // self.groups, channels // self.groups)self.conv1x1 = nn.Conv2d(channels // self.groups, channels // self.groups, kernel_size=1, stride=1, padding=0)self.conv3x3 = nn.Conv2d(channels // self.groups, channels // self.groups, kernel_size=3, stride=1, padding=1)def forward(self, x):b, c, h, w = x.size()group_x = x.reshape(b * self.groups, -1, h, w)  # b*g,c//g,h,wx_h = self.pool_h(group_x)x_w = self.pool_w(group_x).permute(0, 1, 3, 2)hw = self.conv1x1(torch.cat([x_h, x_w], dim=2))x_h, x_w = torch.split(hw, [h, w], dim=2)x1 = self.gn(group_x * x_h.sigmoid() * x_w.permute(0, 1, 3, 2).sigmoid())x2 = self.conv3x3(group_x)x11 = self.softmax(self.agp(x1).reshape(b * self.groups, -1, 1).permute(0, 2, 1))x12 = x2.reshape(b * self.groups, c // self.groups, -1)  # b*g, c//g, hwx21 = self.softmax(self.agp(x2).reshape(b * self.groups, -1, 1).permute(0, 2, 1))x22 = x1.reshape(b * self.groups, c // self.groups, -1)  # b*g, c//g, hwweights = (torch.matmul(x11, x12) + torch.matmul(x21, x22)).reshape(b * self.groups, 1, h, w)return (group_x * weights.sigmoid()).reshape(b, c, h, w)