提供一个简单的深度学习模型(类似 DeepSeek 工作原理的简单示例,比如一个简单的神经网络实现手写数字识别,使用 PyTorch 框架)示例代码
import torch
import torch.nn as nn
import torch.optim as optim
from torchvision import datasets, transforms
from torch.utils.data import DataLoader
# 数据预处理
transform = transforms.Compose([
transforms.ToTensor(),
transforms.Normalize((0.1307,), (0.3081,))
])
# 加载训练集和测试集
train_dataset = datasets.MNIST(root='./data', train=True,
download=True, transform=transform)
test_dataset = datasets.MNIST(root='./data', train=False,
download=True, transform=transform)
# 创建数据加载器
train_loader = DataLoader(train_dataset, batch_size=64, shuffle=True)
test_loader = DataLoader(test_dataset, batch_size=64, shuffle=False)
# 定义神经网络模型
class Net(nn.Module):
def __init__(self):
super(Net, self).__init__()
self.conv1 = nn.Conv2d(1, 16, kernel_size=3, padding=1)
self.relu1 = nn.ReLU()
self.pool = nn.MaxPool2d(2, 2)
self.conv2 = nn.Conv2d(16, 32, kernel_size=3, padding=1)
self.relu2 = nn.ReLU()
self.fc1 = nn.Linear(32 * 7 * 7, 128)
self.relu3 = nn.ReLU()
self.fc2 = nn.Linear(128, 10)
def forward(self, x):
x = self.conv1(x)
x = self.relu1(x)
x = self.pool(x)
x = self.conv2(x)
x = self.relu2(x)
x = self.pool(x)
x = x.view(-1, 32 * 7 * 7)
x = self.fc1(x)
x = self.relu3(x)
x = self.fc2(x)
return x
# 初始化模型、损失函数和优化器
model = Net()
criterion = nn.CrossEntropyLoss()
optimizer = optim.Adam(model.parameters(), lr=0.001)
# 训练模型
num_epochs = 10
for epoch in range(num_epochs):
model.train()
running_loss = 0.0
for batch_idx, (data, target) in enumerate(train_loader):
optimizer.zero_grad()
output = model(data)
loss = criterion(output, target)
loss.backward()
optimizer.step()
running_loss += loss.item()
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()))
# 在测试集上评估模型
model.eval()
test_loss = 0
correct = 0
with torch.no_grad():
for data, target in test_loader:
output = model(data)
test_loss += criterion(output, target).item()
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)))
以上代码构建了一个简单的卷积神经网络用于 MNIST 手写数字识别,包含了数据加载、模型定义、训练和测试等流程。