如何打开CIFAR-10数据集并测试vit
时间: 2024-10-09 10:03:46 浏览: 60
CIFAR-10是一个常用的小型图像分类数据集,包含了10个类别共6万张32x32像素的彩色图片。要在PyTorch中使用Vision Transformer (ViT)模型对CIFAR-10进行训练和测试,首先需要安装必要的库如torch、 torchvision、 einops 和 pytorch-lightning等。
以下是简要步骤:
1. **安装依赖**:
```bash
pip install torch torchvision einops pytorch-lightning
```
2. **加载数据**:
使用`torchvision.datasets.CIFAR10`和`torch.utils.data.DataLoader`来加载和预处理数据:
```python
import torchvision
from torchvision import transforms
transform = transforms.Compose([
transforms.ToTensor(),
transforms.Normalize(mean=[0.4914, 0.4822, 0.4465], std=[0.2023, 0.1994, 0.2010]) # 数据标准化
])
train_dataset = torchvision.datasets.CIFAR10(root='./data', train=True, download=True, transform=transform)
test_dataset = torchvision.datasets.CIFAR10(root='./data', train=False, download=True, transform=transform)
train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=32, shuffle=True, num_workers=2)
test_loader = torch.utils.data.DataLoader(test_dataset, batch_size=32, shuffle=False, num_workers=2)
```
3. **构建ViT模型**:
使用`pytorch_lightning`库创建一个基于ViT的 LightningModule 类,并设置适当的超参数:
```python
from vit_pytorch import ViT
import pytorch_lightning as pl
model = ViT(num_classes=10, image_size=32, patch_size=16, hidden_dim=768, num_layers=12, heads=12)
```
4. **定义损失函数和优化器**:
```python
loss_fn = nn.CrossEntropyLoss()
optimizer = AdamW(model.parameters(), lr=0.001)
```
5. **训练和测试**:
创建一个LightningModule实例,配置训练和验证步骤,然后开始训练和评估模型:
```python
class LitCIFARTransformer(pl.LightningModule):
def __init__(self, model):
super().__init__()
self.model = model
self.loss_fn = loss_fn
def forward(self, x):
return self.model(x)
def training_step(self, batch, batch_idx):
images, labels = batch
outputs = self(images)
loss = self.loss_fn(outputs, labels)
self.log("train_loss", loss)
return loss
def validation_step(self, batch, batch_idx):
... (similar to training_step but without logging)
trainer = pl.Trainer(max_epochs=10, gpus=1 if torch.cuda.is_available() else None)
trainer.fit(LitCIFARTransformer(model), train_loader, test_loader)
```
完成以上步骤后,您就可以使用预训练的ViT对CIFAR-10数据集进行测试了。
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