3.1Regression回歸

import torch
import torch.nn.functional as F
from torch.autograd import Variable
import matplotlib.pyplot as plt"""
創建數據
"""x = torch.unsqueeze(torch.linspace(-1,1,100),dim=1)
y = x.pow(2) + 0.2*torch.rand(x.size()) #增加噪點
x , y = Variable(x),Variable(y)# plt.scatter(x.data.numpy(),y.data.numpy())    #打印數據
# plt.show()"""
搭建網絡
"""
class Net(torch.nn.Module):def __init__(self,n_features,n_hidden,n_out):super(Net, self).__init__()self.hidden = torch.nn.Linear(n_features,n_hidden)self.predict = torch.nn.Linear(n_hidden,n_out)def forward(self,x):x = F.relu(self.hidden(x))x = self.predict(x)return xnet = Net(1,10,1)
# print(net)
plt.ion()   #實時打印的
plt.show()
"""
優化網絡
"""
optimizer = torch.optim.SGD(net.parameters(),lr=0.5)
loss_func = torch.nn.MSELoss()      #MSELoss是用在線性預測
#打印環節
for t in range(100):prediction = net(x)loss = loss_func(prediction,y)optimizer.zero_grad()loss.backward()optimizer.step()if t % 5 ==0:plt.cla()plt.scatter(x.data.numpy(),y.data.numpy())plt.plot(x.data.numpy(),prediction.data.numpy(),'r-',lw=5)plt.text(0.5,0,'Loss=%.4f' % loss.item(),fontdict={'size':20,'color':'red'})       #注意莫老師這里loss.data[0]得換成loss.item()plt.pause(0.1)plt.ioff()
plt.show()

3.2Classification分類

import torch
import torch.nn.functional as F
from torch.autograd import Variable
import matplotlib.pyplot as plt"""
創建數據
"""
n_data = torch.ones(100,2)
x0 = torch.normal(2*n_data,1)
y0 = torch.zeros(100)
x1 = torch.normal(-2*n_data,1)
y1 = torch.ones(100)
x = torch.cat((x0,x1),0).type(torch.FloatTensor)
y = torch.cat((y0,y1),).type(torch.LongTensor)x,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()"""
網絡搭建
"""
class Net(torch.nn.Module):def __init__(self,n_features,n_hidden,n_out):super(Net, self).__init__()self.hidden = torch.nn.Linear(n_features,n_hidden)self.predict = torch.nn.Linear(n_hidden,n_out)def forward(self,x):x = F.relu(self.hidden(x))x = self.predict(x)return xnet = Net(2,10,2)
# print(net)plt.ion()   #實時打印的
plt.show()optimizer = torch.optim.SGD(net.parameters(),lr=0.02)
loss_func = torch.nn.CrossEntropyLoss()     #CrossEntropyLoss用在分類的損失函數中"""
結果打印
"""
for t in range(100):out = net(x)loss = loss_func(out,y)optimizer.zero_grad()loss.backward()optimizer.step()if t % 2 == 0:plt.cla()prediction = torch.max(F.softmax(out),1)[1] #輸出的結果在第二位，因為輸出是二維，例如輸出結果為[0,1],是指最大值為0，類型是1pred_y = prediction.data.numpy().squeeze()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 = sum(pred_y == target_y) / 200plt.text(1.5,-4,'Accuracy=%.2f'%accuracy,fontdict={'size':20,'color':'red'})plt.pause(0.1)plt.ioff()
plt.show()

3.3快速搭建法

import torch
import torch.nn.functional as F
from torch.autograd import Variable
import matplotlib.pyplot as plt"""
創建數據
"""
n_data = torch.ones(100,2)
x0 = torch.normal(2*n_data,1)
y0 = torch.zeros(100)
x1 = torch.normal(-2*n_data,1)
y1 = torch.ones(100)
x = torch.cat((x0,x1),0).type(torch.FloatTensor)
y = torch.cat((y0,y1),).type(torch.LongTensor)x,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()"""
普通網絡搭建
"""
class Net(torch.nn.Module):def __init__(self,n_features,n_hidden,n_out):super(Net, self).__init__()self.hidden = torch.nn.Linear(n_features,n_hidden)self.predict = torch.nn.Linear(n_hidden,n_out)def forward(self,x):x = F.relu(self.hidden(x))x = self.predict(x)return xnet1 = Net(2,10,2)"""
快速網絡搭建
"""
net2 = torch.nn.Sequential(torch.nn.Linear(2,10),torch.nn.ReLU(),torch.nn.Linear(10,2)
)print(net1)
print(net2)

3.4保存提取

import torch
from torch.autograd import  Variable
import matplotlib.pyplot as plt#fake data
x = torch.unsqueeze(torch.linspace(-1,1,100),dim=1)
y = x.pow(2) + 0.2*torch.rand(x.size())
x,y = Variable(x,requires_grad=False),Variable(y,requires_grad=False)"""
保存
"""
def save():net1 = torch.nn.Sequential(torch.nn.Linear(1, 10),torch.nn.ReLU(),torch.nn.Linear(10, 1))optimizer = torch.optim.SGD(net1.parameters(), lr=0.5)loss_func = torch.nn.MSELoss()for t in range(100):prediction = net1(x)loss = loss_func(prediction, y)optimizer.zero_grad()loss.backward()optimizer.step()torch.save(net1,'net.pkl')  #保存網絡torch.save(net1.state_dict(),'net_params.pkl')   #保存參數#畫圖plt.figure(1,figsize=(10,3))plt.subplot(131)plt.title('Net1')plt.scatter(x.data.numpy(),y.data.numpy())plt.plot(x.data.numpy(),prediction.data.numpy(),'r-',lw=5)"""
提取網絡模型
"""
def restore_net():net2 = torch.load('net.pkl')prediction = net2(x)plt.subplot(132)plt.title('Net2')plt.scatter(x.data.numpy(), y.data.numpy())plt.plot(x.data.numpy(), prediction.data.numpy(), 'r-', lw=5)"""
提取網絡參數
"""
def restore_params():net3 = torch.nn.Sequential(torch.nn.Linear(1, 10),torch.nn.ReLU(),torch.nn.Linear(10, 1))net3.load_state_dict(torch.load('net_params.pkl'))prediction = net3(x)plt.subplot(133)plt.title('Net3')plt.scatter(x.data.numpy(), y.data.numpy())plt.plot(x.data.numpy(), prediction.data.numpy(), 'r-', lw=5)plt.show()save()
restore_net()
restore_params()

3.5批數據訓練

import torch
import torch.utils.data as DataBATCH_SIZE = 5x = torch.linspace(1,10,10)
y = torch.linspace(10,1,10)#torch_dataset = Data.TensorDataset(data_tensor=x,target_tensor=y)  #莫老師使用的這個方法在高版本報錯 使用下邊的語句可以解決
torch_dataset = Data.TensorDataset(x,y)loader = Data.DataLoader(dataset=torch_dataset,batch_size=BATCH_SIZE,shuffle=True,#num_workers=2,      #線程數   windows用戶這里要去掉 因為windows系統中沒有Fork函數，多線程會報錯
)for epoch in range(3):for step,(batch_x,batch_y) in enumerate(loader):#trainingprint('Epoch:',epoch,'|Step:',step,'|batch x:',batch_x.numpy(),'|batch y:',batch_y.numpy())

3.6Optimizer優化器

import torch
import torch.nn.functional as F
from torch.autograd import Variable
import matplotlib.pyplot as plt
import torch.utils.data as Data#hyper parameters
LR = 0.01
BATCH_SIZE = 32
EPOCH = 12x = torch.unsqueeze(torch.linspace(-1,1,100),dim=1)
y = x.pow(2) + 0.2*torch.rand(x.size())# plt.scatter(x.numpy(),y.numpy())
# plt.show()torch_dataset = Data.TensorDataset(x,y)
loader = Data.DataLoader(dataset=torch_dataset,batch_size=BATCH_SIZE,shuffle=True)class Net(torch.nn.Module):def __init__(self):super(Net, self).__init__()self.hidden = torch.nn.Linear(1,20)self.predict = torch.nn.Linear(20,1)def forward(self,x):x = F.relu(self.hidden(x))x = self.predict(x)return xnet_SGD = Net()
net_Momentum =  Net()
net_RMSprop =   Net()
net_Adam =  Net()
nets = [net_SGD,net_Momentum,net_RMSprop,net_Adam]opt_SGD = torch.optim.SGD(net_SGD.parameters(),lr=LR)
opt_Momentum = torch.optim.SGD(net_Momentum.parameters(),lr=LR,momentum=0.8)
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]loss_func = torch.nn.MSELoss()
losses_his=[[],[],[],[]]    #記錄損失
for epoch in range(EPOCH):print(epoch)for step,(batch_x,batch_y) in enumerate(loader):#     b_x = Variable(batch_x)   #新版本pytorch不用這個了#     b_y = Variable(batch_y)for net,opt,l_his in zip(nets,optimizers,losses_his):output = net(batch_x)loss = loss_func(output,batch_y)opt.zero_grad()loss.backward()opt.step()l_his.append(loss.item())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.show()