import torch import torch.nn as nn import torch.optim as optim # 定义数据 x1 = torch.tensor([0, 2.8, 5.6, 8.4, 11.2, 14, 16.8], dtype=torch.float32) x2 = torch.tensor([0, 20, 387, 680, 783, 850, 1120], dtype=torch.float32) y = torch.tensor([0, 87.94, 2447.78, 5253, 6625.75, 7868.45, 12012], dtype=torch.float32) # 定义模型 class LinearRegression(nn.Module): def __init__(self): super(LinearRegression, self).__init__() self.linear = nn.Linear(2, 1) # 输入特征维度为2，输出特征维度为1 def forward(self, x): out = self.linear(x) return out model = LinearRegression() # 定义损失函数和优化器 criterion = nn.MSELoss() optimizer = optim.SGD(model.parameters(), lr=0.01) # 训练模型 num_epochs = 1000 for epoch in range(num_epochs): inputs = torch.stack([x1, x2], dim=1) # 将两个自变量堆叠在一起 outputs = model(inputs) loss = criterion(outputs.squeeze(), y) # 计算损失 optimizer.zero_grad() loss.backward() optimizer.step() if (epoch+1) % 100 == 0: print('Epoch [{}/{}], Loss: {:.4f}'.format(epoch+1, num_epochs, loss.item())) # 打印模型参数 print("模型参数:") for name, param in model.named_parameters(): if param.requires_grad: print(name, param.data) # 使用模型进行预测 test_input = torch.tensor([[6, 12]], dtype=torch.float32) predicted = model(test_input) print("预测结果:", predicted.item())

你的代码看起来很不错！你根据自己的数据设置了x1、x2和y的值，并定义了一个继承自nn.Module的线性回归模型。你还使用了均方误差损失函数和随机梯度下降优化器进行训练，并打印了训练过程中的损失值。最后，你使用训练好的模型进行了预测并打印了预测结果。

这个代码示例中使用的数据和模型都是符合线性回归的特征，所以应该能得到较好的结果。如果你有任何其他问题或者需要进一步的帮助，请随时告诉我！

相关问题

import torch import torch.nn.functional as F import torch.optim as optim from torchvision import transforms from torchvision import datasets from torch.utils. data import DataI oader 补全代码

下面是一个基本的 PyTorch MNIST 数据集训练代码示例，包括数据加载、模型定义、优化器和损失函数的定义以及训练过程。

import torch
import torch.nn as nn
import torch.nn.functional as F
import torch.optim as optim
from torchvision import transforms
from torchvision import datasets
from torch.utils.data import DataLoader

# 定义数据预处理
transform = transforms.Compose([
    transforms.ToTensor(),
    transforms.Normalize((0.1307,), (0.3081,))
])

# 加载数据集
train_dataset = datasets.MNIST('data', train=True, download=True, transform=transform)
test_dataset = datasets.MNIST('data', train=False, download=True, transform=transform)
train_loader = DataLoader(train_dataset, batch_size=64, shuffle=True)
test_loader = DataLoader(test_dataset, batch_size=64, shuffle=False)

# 定义模型
class Net(nn.Module):
    def __init__(self):
        super(Net, self).__init__()
        self.conv1 = nn.Conv2d(1, 10, kernel_size=5)
        self.conv2 = nn.Conv2d(10, 20, kernel_size=5)
        self.fc1 = nn.Linear(320, 50)
        self.fc2 = nn.Linear(50, 10)

    def forward(self, x):
        x = F.relu(F.max_pool2d(self.conv1(x), 2))
        x = F.relu(F.max_pool2d(self.conv2(x), 2))
        x = x.view(-1, 320)
        x = F.relu(self.fc1(x))
        x = self.fc2(x)
        return F.log_softmax(x, dim=1)

net = Net()

# 定义优化器和损失函数
optimizer = optim.SGD(net.parameters(), lr=0.01, momentum=0.5)
criterion = nn.CrossEntropyLoss()

# 训练模型
def train(epoch):
    net.train()
    for batch_idx, (data, target) in enumerate(train_loader):
        optimizer.zero_grad()
        output = net(data)
        loss = criterion(output, target)
        loss.backward()
        optimizer.step()
        if batch_idx % 10 == 0:
            print('Train Epoch: {} [{}/{} ({:.0f}%)]\tLoss: {:.6f}'.format(
                epoch, batch_idx * len(data), len(train_loader.dataset),
                100. * batch_idx / len(train_loader), loss.item()))

def test():
    net.eval()
    test_loss = 0
    correct = 0
    with torch.no_grad():
        for data, target in test_loader:
            output = net(data)
            test_loss += criterion(output, target)
            pred = output.argmax(dim=1, keepdim=True)
            correct += pred.eq(target.view_as(pred)).sum().item()

    test_loss /= len(test_loader.dataset)
    print('\nTest set: Average loss: {:.4f}, Accuracy: {}/{} ({:.0f}%)\n'.format(
        test_loss, correct, len(test_loader.dataset),
        100. * correct / len(test_loader.dataset)))

for epoch in range(1, 5):
    train(epoch)
    test()

这是一个简单的卷积神经网络模型，用于对 MNIST 手写数字进行分类。训练过程中使用了交叉熵损失函数和随机梯度下降优化器。

import torch.optim as optim

from typing import List,Tuple
import torch
import torch.nn as nn
import torch.nn.functional as F

class Net(nn.Module):
def __init__(self, input_size:int, hidden_size:List[int], output_size:int, dropout:float):
super(Net, self).__init__()
self.input_size = input_size
self.hidden_size = hidden_size
self.output_size = output_size
self.dropout = dropout

# Construct the hidden layers
self.hidden_layers = nn.ModuleList()
for i in range(len(hidden_size)):
if i == 0:
self.hidden_layers.append(nn.Linear(input_size, hidden_size[i]))
else:
self.hidden_layers.append(nn.Linear(hidden_size[i-1], hidden_size[i]))

# Construct the output layer
self.output_layer = nn.Linear(hidden_size[-1], output_size)

# Set up the dropout layer
self.dropout_layer = nn.Dropout(p=dropout)

def forward(self, x:torch.Tensor) -> torch.Tensor:
# Pass the input through the hidden layers
for layer in self.hidden_layers:
x = F.relu(layer(x))
x = self.dropout_layer(x)

# Pass the output from the last hidden layer through the output layer
x = self.output_layer(x)

return x

def train_model(model:Net, train_data:Tuple[torch.Tensor, torch.Tensor],
test_data:Tuple[torch.Tensor, torch.Tensor],
batch_size:int, num_epochs:int, learning_rate:float):

# Extract the inputs and labels from the training data
train_inputs, train_labels = train_data

# Define the loss function and optimizer
criterion = nn.CrossEntropyLoss()
optimizer = optim.Adam(model.parameters(), lr=learning_rate)

# Loop over the training data for the specified number of epochs
for epoch in range(num_epochs):
# Shuffle the training data
perm = torch.randperm(train_inputs.size(0))
train_inputs = train_inputs[perm]
train_labels = train_labels[perm]

# Loop over the training data in batches
for i in range(0, train_inputs.size(0), batch_size):
# Extract the current batch of data
inputs = train_inputs[i:i+batch_size]
labels = train_labels[i:i+batch_size]

# Zero the gradients
optimizer.zero_grad()

# Forward pass
outputs = model(inputs)
loss = criterion(outputs, labels)

# Backward pass and update parameters
loss.backward()
optimizer.step()

# Evaluate the model on the test data
test_inputs, test_labels = test_data
test_outputs = model(test_inputs)
test_loss = criterion(test_outputs, test_labels)
test_accuracy = accuracy(test_outputs, test_labels)

# Print the epoch number, training loss, and test accuracy
print(f"Epoch {epoch+1}/{num_epochs}: Train loss={loss:.4f}, Test loss={test_loss:.4f}, Test accuracy={test_accuracy:.4f}")

def accuracy(outputs:torch.Tensor, labels:torch.Tensor) -> float:
predictions = torch.argmax(outputs, dim=1)
correct_predictions = torch.sum(predictions == labels)
accuracy = correct_predictions.float() / labels.size(0)
return accuracy.item()