pytorch resnet实现

官方github上已经有了pytorch基础模型的实现，链接

但是其中一些模型，尤其是resnet，都是用函数生成的各个层，自己看起来是真的难受！

所以自己按照caffe的样子，写一个pytorch的resnet18模型，当然和1000分类模型不同，模型做了一些修改，输入48*48的3通道图片，输出7类。

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

class ResNet18Model(nn.Module):
        def __init__(self):
                super().__init__()

                self.bn64_0 = nn.BatchNorm2d(64)
                self.bn64_1 = nn.BatchNorm2d(64)
                self.bn64_2 = nn.BatchNorm2d(64)
                self.bn64_3 = nn.BatchNorm2d(64)
                self.bn64_4 = nn.BatchNorm2d(64)


                self.bn128_0 = nn.BatchNorm2d(128)
                self.bn128_1 = nn.BatchNorm2d(128)
                self.bn128_2 = nn.BatchNorm2d(128)
                self.bn128_3 = nn.BatchNorm2d(128)

                self.bn256_0 = nn.BatchNorm2d(256)
                self.bn256_1 = nn.BatchNorm2d(256)
                self.bn256_2 = nn.BatchNorm2d(256)
                self.bn256_3 = nn.BatchNorm2d(256)

                self.bn512_0 = nn.BatchNorm2d(512)
                self.bn512_1 = nn.BatchNorm2d(512)
                self.bn512_2 = nn.BatchNorm2d(512)
                self.bn512_3 = nn.BatchNorm2d(512)


                self.shortcut_straight_0 = nn.Sequential()
                self.shortcut_straight_1 = nn.Sequential()
                self.shortcut_straight_2 = nn.Sequential()
                self.shortcut_straight_3 = nn.Sequential()
                self.shortcut_straight_4 = nn.Sequential()


                self.shortcut_conv_bn_64_128_0 = nn.Sequential(nn.Conv2d(64, 128, kernel_size=1, stride=2, bias=False),nn.BatchNorm2d(128))

                self.shortcut_conv_bn_128_256_0 = nn.Sequential(nn.Conv2d(128, 256, kernel_size=1, stride=2, bias=False),nn.BatchNorm2d(256))

                self.shortcut_conv_bn_256_512_0 = nn.Sequential(nn.Conv2d(256, 512, kernel_size=1, stride=2, bias=False),nn.BatchNorm2d(512))


                self.conv_w3_h3_in3_out64_s1_p1_0 = nn.Conv2d(3, 64, kernel_size=3, stride=1, padding=1, bias=False)

                self.conv_w3_h3_in64_out64_s1_p1_0 = nn.Conv2d(64, 64, kernel_size=3, stride=1, padding=1, bias=False)
                self.conv_w3_h3_in64_out64_s1_p1_1 = nn.Conv2d(64, 64, kernel_size=3, stride=1, padding=1, bias=False)
                self.conv_w3_h3_in64_out64_s1_p1_2 = nn.Conv2d(64, 64, kernel_size=3, stride=1, padding=1, bias=False)
                self.conv_w3_h3_in64_out64_s1_p1_3 = nn.Conv2d(64, 64, kernel_size=3, stride=1, padding=1, bias=False)


                self.conv_w3_h3_in64_out128_s2_p1_0 = nn.Conv2d(64, 128, kernel_size=3, stride=2, padding=1, bias=False)

                self.conv_w3_h3_in128_out128_s1_p1_0 = nn.Conv2d(128, 128, kernel_size=3, stride=1, padding=1, bias=False)
                self.conv_w3_h3_in128_out128_s1_p1_1 = nn.Conv2d(128, 128, kernel_size=3, stride=1, padding=1, bias=False)
                self.conv_w3_h3_in128_out128_s1_p1_2 = nn.Conv2d(128, 128, kernel_size=3, stride=1, padding=1, bias=False)


                self.conv_w3_h3_in128_out256_s2_p1_0 = nn.Conv2d(128, 256, kernel_size=3, stride=2, padding=1, bias=False)

                self.conv_w3_h3_in256_out256_s1_p1_0 = nn.Conv2d(256, 256, kernel_size=3, stride=1, padding=1, bias=False)
                self.conv_w3_h3_in256_out256_s1_p1_1 = nn.Conv2d(256, 256, kernel_size=3, stride=1, padding=1, bias=False)
                self.conv_w3_h3_in256_out256_s1_p1_2 = nn.Conv2d(256, 256, kernel_size=3, stride=1, padding=1, bias=False)


                self.conv_w3_h3_in256_out512_s2_p1_0 = nn.Conv2d(256, 512, kernel_size=3, stride=2, padding=1, bias=False)

                self.conv_w3_h3_in512_out512_s1_p1_0 = nn.Conv2d(512, 512, kernel_size=3, stride=1, padding=1, bias=False)
                self.conv_w3_h3_in512_out512_s1_p1_1 = nn.Conv2d(512, 512, kernel_size=3, stride=1, padding=1, bias=False)
                self.conv_w3_h3_in512_out512_s1_p1_2 = nn.Conv2d(512, 512, kernel_size=3, stride=1, padding=1, bias=False)


                self.avg_pool_0 = nn.AdaptiveAvgPool2d((1, 1))
                self.fc_512_7_0 = nn.Linear(512, 7)
                self.dropout_0 = nn.Dropout(p=0.5)




        def forward(self, x):

                # 48*48*3
                t = self.conv_w3_h3_in3_out64_s1_p1_0(x) #48*48*64
                t = self.bn64_0(t)
                y1 = F.relu(t)


                t = self.conv_w3_h3_in64_out64_s1_p1_0(y1) #48*48*64
                t = self.bn64_1(t) 
                y2 = F.relu(t)

                t = self.conv_w3_h3_in64_out64_s1_p1_1(y2) #48*48*64
                t = self.bn64_2(t)
                t += self.shortcut_straight_0(y1)
                y3 = F.relu(t)


                t = self.conv_w3_h3_in64_out64_s1_p1_2(y3) #48*48*64
                t = self.bn64_3(t)
                y4 = F.relu(t)

                t = self.conv_w3_h3_in64_out64_s1_p1_3(y4) #48*48*64
                t = self.bn64_4(t)
                t += self.shortcut_straight_1(y3)
                y5 = F.relu(t)


                t = self.conv_w3_h3_in64_out128_s2_p1_0(y5) #24*24*128
                t = self.bn128_0(t)
                y6 = F.relu(t)

                t = self.conv_w3_h3_in128_out128_s1_p1_0(y6) #24*24*128
                t = self.bn128_1(t)
                t += self.shortcut_conv_bn_64_128_0(y5)
                y7 = F.relu(t)


                t = self.conv_w3_h3_in128_out128_s1_p1_1(y7) #24*24*128
                t = self.bn128_2(t)
                y8 = F.relu(t)

                t = self.conv_w3_h3_in128_out128_s1_p1_2(y8) #24*24*128
                t = self.bn128_3(t)
                t += self.shortcut_straight_2(y7)
                y9 = F.relu(t)


                t = self.conv_w3_h3_in128_out256_s2_p1_0(y9) #12*12*256
                t = self.bn256_0(t)
                y10 = F.relu(t)

                t = self.conv_w3_h3_in256_out256_s1_p1_0(y10) #12*12*256
                t = self.bn256_1(t)
                t += self.shortcut_conv_bn_128_256_0(y9)
                y11 = F.relu(t)


                t = self.conv_w3_h3_in256_out256_s1_p1_1(y11) #12*12*256
                t = self.bn256_2(t)
                y12 = F.relu(t)

                t = self.conv_w3_h3_in256_out256_s1_p1_2(y12) #12*12*256
                t = self.bn256_3(t)
                t += self.shortcut_straight_3(y11)
                y13 = F.relu(t)


                t = self.conv_w3_h3_in256_out512_s2_p1_0(y13) #6*6*512
                t = self.bn512_0(t)
                y14 = F.relu(t)

                t = self.conv_w3_h3_in512_out512_s1_p1_0(y14) #6*6*512
                t = self.bn512_1(t)
                t += self.shortcut_conv_bn_256_512_0(y13)
                y15 = F.relu(t)


                t = self.conv_w3_h3_in512_out512_s1_p1_1(y15) #6*6*512
                t = self.bn512_2(t)
                y16 = F.relu(t)

                t = self.conv_w3_h3_in512_out512_s1_p1_2(y16) #6*6*512
                t = self.bn512_3(t)
                t += self.shortcut_straight_4(y15)
                y17 = F.relu(t)


                out = self.avg_pool_0(y17) #1*1*512             
                out = out.view(out.size(0), -1)
                out = self.dropout_0(out)
                out = self.fc_512_7_0(out)

                return out



if __name__ == '__main__':
        net = ResNet18Model()
        # print(net)

        import torch
        net_in = torch.rand(1, 3, 48, 48)
        net_out = net(net_in)
        print(net_out)
        print(net_out.size())