PyTorch Dataloader - 枚举时列表不可调用错误

Question

当迭代 PyTorch 数据加载器时，例如

# define dataset, dataloader
train_data = datasets.ImageFolder(data_dir + '/train', transform=train_transforms)
test_data = datasets.ImageFolder(data_dir + '/test', transform=test_transforms)
trainloader = torch.utils.data.DataLoader(train_data, batch_size=64, shuffle=True)
testloader = torch.utils.data.DataLoader(test_data, batch_size=64)

# define model, optimizer, loss
# not included - irrelevant to the question

for ii, (inputs, labels) in enumerate(trainloader):

    # Move input and label tensors to the GPU
    inputs, labels = inputs.to(device), labels.to(device)

    start = time.time()

    outputs = model.forward(inputs)
    loss = criterion(outputs, labels)
    loss.backward()

我TypeError: 'list' object is not callable在这条线上得到了

for ii, (inputs, labels) in enumerate(trainloader):

我忘记了什么愚蠢的事情？

Answer 1

你记得打电话吗transforms.Compose您的变换列表？

在这一行

train_data = datasets.ImageFolder(data_dir + '/train', transform=train_transforms)

这transform参数需要一个可调用对象，而不是一个列表。

例如，这是错误的：

train_transforms = [
    transforms.RandomResizedCrop(224),
    transforms.RandomHorizontalFlip(),
    transforms.ToTensor(),
    transforms.Normalize([0.485, 0.456, 0.406], [0.229, 0.224, 0.225])]

它应该看起来像这样

train_transforms = transforms.Compose([
    transforms.RandomResizedCrop(224),
    transforms.RandomHorizontalFlip(),
    transforms.ToTensor(),
    transforms.Normalize([0.485, 0.456, 0.406], [0.229, 0.224, 0.225])])