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 专栏相关代码：目前售价售价69.9，改进点80+

专栏介绍：YOLOv9改进系列 | 包含深度学习最新创新，助力高效涨点！！！

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1. SPPELAN

        SPPELAN是YOLOv9作者在SPPF的基础上创新的模块（增加了一次最大池化），整体结构及代码如下，代码中SP模块即为最大池化。

class SP(nn.Module):
    def __init__(self, k=3, s=1):
        super(SP, self).__init__()
        self.m = nn.MaxPool2d(kernel_size=k, stride=s, padding=k // 2)

    def forward(self, x):
        return self.m(x)


class SPPELAN(nn.Module):
    # spp-elan
    def __init__(self, c1, c2, c3):  # ch_in, ch_out, number, shortcut, groups, expansion
        super().__init__()
        self.c = c3
        self.cv1 = Conv(c1, c3, 1, 1)
        self.cv2 = SP(5)
        self.cv3 = SP(5)
        self.cv4 = SP(5)
        self.cv5 = Conv(4*c3, c2, 1, 1)

    def forward(self, x):
        y = [self.cv1(x)]
        y.extend(m(y[-1]) for m in [self.cv2, self.cv3, self.cv4])
        return self.cv5(torch.cat(y, 1))

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