|
- import torch
- import numpy as np
- from torch import nn
- from torch.autograd import Variable
- import torch.nn.functional as F
- import matplotlib.pyplot as plt
- import matplotlib as mpl
-
- plt.rcParams['font.sans-serif']=['SimHei']
- plt.rcParams['axes.unicode_minus'] = False
-
- #%matplotlib inline
- np.random.seed(1)
- m = 400 # 样本数量
- N = int(m/2) # 每一类的点的个数
- D = 2 # 维度
- x = np.zeros((m, D))
- y = np.zeros((m, 1), dtype='uint8') # label 向量， 0 表示红色， 1 表示蓝色
- a = 4
-
- criterion = nn.BCEWithLogitsLoss()
-
- # 生成两类数据
- for j in range(2):
- ix = range(N*j,N*(j+1))
- t = np.linspace(j*3.12,(j+1)*3.12,N) + np.random.randn(N)*0.2 # theta
- r = a*np.sin(4*t) + np.random.randn(N)*0.2 # radius
- x[ix] = np.c_[r*np.sin(t), r*np.cos(t)]
- y[ix] = j
-
-
- def plot_decision_boundary(model, x, y):
- # Set min and max values and give it some padding
- x_min, x_max = x[:, 0].min() - 1, x[:, 0].max() + 1
- y_min, y_max = x[:, 1].min() - 1, x[:, 1].max() + 1
- h = 0.01
- # Generate a grid of points with distance h between them
- xx, yy = np.meshgrid(np.arange(x_min, x_max, h), np.arange(y_min,y_max, h))
-
- # Predict the function value for the whole grid .c_ 按行连接两个矩阵，左右相加。
- Z = model(np.c_[xx.ravel(), yy.ravel()])
- Z = Z.reshape(xx.shape)
- # Plot the contour and training examples
- plt.contourf(xx, yy, Z, cmap=plt.cm.Spectral)
- plt.ylabel("x2")
- plt.xlabel("x1")
- for i in range(m):
- if y[i] == 0:
- plt.scatter(x[i, 0], x[i, 1], marker='8',c=0, s=40, cmap=plt.cm.Spectral)
- else:
- plt.scatter(x[i, 0], x[i, 1], marker='^',c=1, s=40)
-
- #尝试用逻辑回归解决
- x = torch.from_numpy(x).float()
- y = torch.from_numpy(y).float()
-
-
- # Sequential
- seq_net = nn.Sequential(
- nn.Linear(2, 4), # PyTorch 中的线性层， wx + b
- nn.Tanh(),
- nn.Linear(4, 1)
- )
-
- # 序列模块可以通过索引访问每一层
- seq_net[0] # 第一层
-
- # 打印出第一层的权重
- w0 = seq_net[0].weight
- print(w0)
-
-
- # 通过 parameters 可以取得模型的参数
- param = seq_net.parameters()
- # 定义优化器
- optim = torch.optim.SGD(param, 1.)
-
- # 训练 10000 次
- for e in range(10000):
- # 网络正向计算
- out = seq_net(Variable(x))
- # 计算误差
- loss = criterion(out, Variable(y))
- # 反向传播、 更新权重
- optim.zero_grad()
- loss.backward()
- optim.step()
- # 打印损失
- if (e + 1) % 1000 == 0:
- print('epoch: {}, loss: {}'.format(e+1, loss.item()))
-
-
- def plot_seq(x):
- out = F.sigmoid(seq_net(Variable(torch.from_numpy(x).float()))).data.numpy()
- out = (out > 0.5) * 1
- return out
-
- plot_decision_boundary(lambda x: plot_seq(x), x.numpy(), y.numpy())
- mpl.rcParams['font.family'] = 'SimHei'
- plt.rcParams['axes.unicode_minus'] = False
-
- # plt.title('序列化网络')
- # plt.savefig('fig-res-8.5.pdf')
- plt.title('模块定义网络')
- plt.savefig('fig-res-8.6.pdf')
- plt.show()
- torch.save(seq_net, 'save_seq_net.pth')
|
