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（1）代码中使用的函数简要介绍

torch.normal  #张量里面的随机数是从相互独立的正态分布中随机生成的。torch.cat     #将两个张量（tensor）拼接在一起

（2）代码

import torchfrom torch.autograd import Variableimport torch.nn.functional as Fimport matplotlib.pyplot as plt# torch.manual_seed(1)    # reproducible#制造训练数据n_data = torch.ones(100, 2)x0 = torch.normal(2*n_data, 1)      # class0 x data (tensor), shape=(100, 2)y0 = torch.zeros(100)               # class0 y data (tensor), shape=(100, 1)x1 = torch.normal(-2*n_data, 1)     # class1 x data (tensor), shape=(100, 2)y1 = torch.ones(100)                # class1 y data (tensor), shape=(100, 1)x = torch.cat((x0, x1), 0).type(torch.FloatTensor)  # shape (200, 2) FloatTensor = 32-bit floatingy = torch.cat((y0, y1), ).type(torch.LongTensor)    # shape (200,) LongTensor = 64-bit integer'''# The code below is deprecated in Pytorch 0.4. Now, autograd directly supports tensorsx, y = Variable(x), Variable(y)plt.scatter(x.data.numpy()[:, 0], x.data.numpy()[:, 1], c=y.data.numpy(), s=100, lw=0, cmap='RdYlGn')plt.show()'''class Net(torch.nn.Module):    def __init__(self, n_feature, n_hidden, n_output):        super(Net, self).__init__()        self.hidden = torch.nn.Linear(n_feature, n_hidden)   # hidden layer        self.out = torch.nn.Linear(n_hidden, n_output)   # output layer    def forward(self, x):        x = F.relu(self.hidden(x))      # activation function for hidden layer        x = self.out(x)        return xnet = Net(n_feature=2, n_hidden=10, n_output=2)     # define the networkprint(net)  # net architectureoptimizer = torch.optim.SGD(net.parameters(), lr=0.02)loss_func = torch.nn.CrossEntropyLoss()  # the target label is NOT an one-hottedplt.ion()   # something about plottingfor t in range(1000):    out = net(x)                 # input x and predict based on x    loss = loss_func(out, y)     # must be (1. nn output, 2. target), the target label is NOT one-hotted    optimizer.zero_grad()   # clear gradients for next train    loss.backward()         # backpropagation, compute gradients    optimizer.step()        # apply gradients    if t % 2 == 0:        # plot and show learning process        plt.cla()        prediction = torch.max(out, 1)[1]        pred_y = prediction.data.numpy()        target_y = y.data.numpy()        plt.scatter(x.data.numpy()[:, 0], x.data.numpy()[:, 1], c=pred_y, s=100, lw=0, cmap='RdYlGn')        accuracy = float((pred_y == target_y).astype(int).sum()) / float(target_y.size)        plt.text(1.5, -4, 'Accuracy=%.2f' % accuracy, fontdict={'size': 20, 'color':  'red'})        plt.pause(1)plt.ioff()plt.show()

（3）代码运行结果

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