今天我们讲解class的定义和实现：

class Dec(nn.Module):#继承nn.Module类
    def __init__(self, ***, ***):#构建模块
        super(Dec, self).__init__()#父类初始化
        self.***= ***
        self.***= ***
        
    def forward(self, x, ***):#组装
        x = ***
        return self.***(x)
        
    def initialize_weights(self):#权值初始化
        ***

net = Dec()#实例化
outputs = net(inputs)

torch.nn.Module
torch.nn

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

class Model(nn.Module):
    def __init__(self):
        super().__init__()
        self.conv1 = nn.Conv2d(1, 20, 5)
        self.conv2 = nn.Conv2d(20, 20, 5)

    def forward(self, x):
        x = F.relu(self.conv1(x))
        return F.relu(self.conv2(x))

下一节我们讲怎么使用nn.Sequential定义模型