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优化器的参数有待进一步了解import torchfrom torch.autograd import Variableimport torch.nn.functional as Fimport matplotlib.pyplot as pltimport torch.utils.data as Data# super paramLR = 0.01BATCH_SIZE=32EPOCH=12x = torch.unsqueeze(torch.linspace(-1,1,1000),dim = 1) #压缩为2维,因为torch 中 只会处理二维的数据y = x.pow(2) + 0.2 * torch.rand(x.size())print(x.numpy(),y.numpy())torch_dataset = Data.TensorDataset(x, y)loader = Data.DataLoader( dataset = torch_dataset, batch_size = BATCH_SIZE, shuffle = True,# true表示数据每次epoch是是打乱顺序抽样的 num_workers = 2, # 每次训练有两个线程进行的????? 改成 1 和 2 暂时没看出区别)class Net(torch.nn.Module): # 继承 torch 的 Module def __init__(self): super(Net, self).__init__() # 继承 __init__ 功能 # 定义每层用什么样的形式 self.hidden = torch.nn.Linear(1,20) # 隐藏层线性输出 self.predict = torch.nn.Linear(20,1) # 输出层线性输出 def forward(self, x): # 这同时也是 Module 中的 forward 功能 # 正向传播输入值, 神经网络分析出输出值 x = F.relu(self.hidden(x)) # 激励函数(隐藏层的线性值) x = self.predict(x) # 输出值 return xnet_SGD = Net()net_Momentum = Net()net_RMSProp = Net()net_Adam= Net()nets = [net_SGD,net_Momentum,net_RMSProp,net_Adam] # 一个比一个高级opt_SGD = torch.optim.SGD(net_SGD.parameters(),lr=LR)opt_Momentum = torch.optim.SGD(net_Momentum.parameters(),lr = LR,momentum=0.8) # 是SGD的改进,加了动量效果opt_RMSProp = torch.optim.RMSprop(net_RMSProp.parameters(),lr=LR,alpha=0.9)opt_Adam= torch.optim.Adam(net_Adam.parameters(),lr=LR,betas=(0.9,0.99))optimizers = [opt_SGD, opt_Momentum, opt_RMSProp, opt_Adam]# 比较这4个优化器会发现,并不一定越高级的效率越高,需要自己找适合自己数据的优化器loss_func = torch.nn.MSELoss()losses_his = [[],[],[],[]]if __name__ == '__main__': # EPOCH + win10 需要if main函数才能正确运行, for epoch in range(EPOCH): print(epoch) for step,(batch_x,batch_y) in enumerate(loader): b_x = Variable(batch_x) b_y = Variable(batch_y) for net,opt,l_his in zip(nets, optimizers, losses_his): output = net(b_x) # get_out for every net loss = loss_func(output,b_y) # compute loss for every net opt.zero_grad() loss.backward() opt.step() # apply gradient l_his.append(loss.data[0]) # loss recoder labels = ['SGD','Momentum','RMSProp','Adam'] for i,l_his in enumerate(losses_his): plt.plot(l_his,label=labels[i]) plt.legend(loc='best') plt.xlabel('Steps') plt.ylabel('Loss') plt.ylim = ((0,0.2)) plt.show()