用python代码实现基于手写数字识别数据集MNIST的测试集(10000张图片)实验用Pytorch框架实现卷积神经网络的搭建。使用自注意力模型替换卷积神经网络中的一层或多层。调整深层架构相关超参数使模型能正常运行并优化模型。进行十折交叉验证并汇报最终识别正确率。以图的形式汇报随机搜索优化过程中训练和测试错误的变化。
时间: 2024-02-01 13:15:44 浏览: 67
这是一个非常复杂的任务,需要大量代码实现和数据处理。以下是简要的步骤概述:
1. 数据处理:下载MNIST数据集并将其转换为PyTorch数据集,并将其拆分为训练集和测试集。使用数据增强技术(如旋转、翻转、缩放等)来增加数据量和多样性。
2. 构建模型:使用PyTorch构建卷积神经网络模型,使用自注意力模型替换其中的一层或多层。调整深层架构相关超参数,如层数、卷积核大小、池化大小等,以优化模型性能。
3. 训练模型:使用训练集对模型进行训练,并使用验证集来调整超参数。使用十折交叉验证来评估模型的泛化能力。
4. 测试模型:使用测试集对模型进行测试,并计算模型的准确性。在测试过程中,记录训练和测试错误的变化,并以图的形式汇报结果。
以下是一个基本的代码框架,用于实现这个任务:
```python
import torch
import torch.nn as nn
import torch.optim as optim
import torchvision.transforms as transforms
import torchvision.datasets as datasets
from torch.utils.data import DataLoader
from sklearn.model_selection import KFold
# 数据处理
transforms = transforms.Compose([
transforms.ToTensor(),
transforms.Normalize((0.1307,), (0.3081,))
])
train_dataset = datasets.MNIST(root='./data', train=True, download=True, transform=transforms)
test_dataset = datasets.MNIST(root='./data', train=False, download=True, transform=transforms)
# 构建模型
class Model(nn.Module):
def __init__(self):
super(Model, self).__init__()
self.conv1 = nn.Conv2d(1, 32, kernel_size=3, padding=1)
self.attn = nn.MultiheadAttention(embed_dim=32, num_heads=4)
self.conv2 = nn.Conv2d(32, 64, kernel_size=3, padding=1)
self.fc1 = nn.Linear(64*7*7, 128)
self.fc2 = nn.Linear(128, 10)
def forward(self, x):
x = nn.functional.relu(self.conv1(x))
x = x.view(-1, 32, 28*28).transpose(0, 2, 1)
x, _ = self.attn(x, x, x)
x = x.transpose(0, 2, 1).view(-1, 32, 28, 28)
x = nn.functional.relu(self.conv2(x))
x = nn.functional.max_pool2d(x, kernel_size=2)
x = x.view(-1, 64*7*7)
x = nn.functional.relu(self.fc1(x))
x = self.fc2(x)
return x
# 训练和测试函数
def train(model, train_loader, optimizer, criterion):
model.train()
running_loss = 0.0
for i, (inputs, labels) in enumerate(train_loader):
optimizer.zero_grad()
outputs = model(inputs)
loss = criterion(outputs, labels)
loss.backward()
optimizer.step()
running_loss += loss.item()
return running_loss / len(train_loader)
def test(model, test_loader, criterion):
model.eval()
correct = 0
total_loss = 0.0
with torch.no_grad():
for inputs, labels in test_loader:
outputs = model(inputs)
total_loss += criterion(outputs, labels).item()
_, predicted = torch.max(outputs.data, 1)
correct += (predicted == labels).sum().item()
return correct / len(test_loader.dataset), total_loss / len(test_loader)
# 训练和测试循环
def train_loop(model, train_loader, test_loader, optimizer, criterion, num_epochs=10):
train_losses = []
test_losses = []
test_accs = []
for epoch in range(num_epochs):
train_loss = train(model, train_loader, optimizer, criterion)
train_losses.append(train_loss)
test_acc, test_loss = test(model, test_loader, criterion)
test_losses.append(test_loss)
test_accs.append(test_acc)
print('Epoch [{}/{}], Train Loss: {:.4f}, Test Loss: {:.4f}, Test Acc: {:.4f}'.format(epoch+1, num_epochs, train_loss, test_loss, test_acc))
return train_losses, test_losses, test_accs
# 交叉验证循环
def cross_validation(model, dataset, num_folds=10, num_epochs=10, batch_size=64, lr=0.01):
kfold = KFold(n_splits=num_folds, shuffle=True)
fold_results = []
for fold, (train_idx, test_idx) in enumerate(kfold.split(dataset)):
print('Fold:', fold+1)
train_dataset = torch.utils.data.Subset(dataset, train_idx)
test_dataset = torch.utils.data.Subset(dataset, test_idx)
train_loader = DataLoader(train_dataset, batch_size=batch_size, shuffle=True)
test_loader = DataLoader(test_dataset, batch_size=batch_size, shuffle=False)
model.apply(weights_init)
optimizer = optim.SGD(model.parameters(), lr=lr, momentum=0.9)
criterion = nn.CrossEntropyLoss()
train_losses, test_losses, test_accs = train_loop(model, train_loader, test_loader, optimizer, criterion, num_epochs=num_epochs)
fold_results.append((train_losses, test_losses, test_accs))
return fold_results
# 训练和测试
model = Model()
results = cross_validation(model, train_dataset, num_folds=10, num_epochs=10, batch_size=64, lr=0.01)
# 绘制训练和测试错误的变化图
import matplotlib.pyplot as plt
plt.figure(figsize=(10, 5))
for i, (train_losses, test_losses, test_accs) in enumerate(results):
plt.subplot(2, 5, i+1)
plt.plot(train_losses, label='Train')
plt.plot(test_losses, label='Test')
plt.title('Fold {}'.format(i+1))
plt.tight_layout()
plt.show()
# 汇报最终识别正确率
test_dataset = datasets.MNIST(root='./data', train=False, download=True, transform=transforms)
test_loader = DataLoader(test_dataset, batch_size=64, shuffle=False)
model.eval()
with torch.no_grad():
correct = 0
for inputs, labels in test_loader:
outputs = model(inputs)
_, predicted = torch.max(outputs.data, 1)
correct += (predicted == labels).sum().item()
acc = correct / len(test_loader.dataset)
print('Test Accuracy:', acc)
```
希望这可以帮助你开始实现这个任务。
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