Dataloader对象无法下标的问题

Question

我现在正在使用Pytorch运行Python程序。我使用自己的数据集，而不是torch.data.dataset。我从特征提取中提取的泡菜文件中下载数据。但是出现以下错误：

Traceback (most recent call last):
  File "C:\Users\hp\Downloads\efficient_densenet_pytorch-master\demo-emotion.py", line 326, in <module>
    fire.Fire(demo)
  File "C:\Users\hp\Anaconda3\envs\tf-gpu\lib\site-packages\fire\core.py", line 138, in Fire
    component_trace = _Fire(component, args, parsed_flag_args, context, name)
  File "C:\Users\hp\Anaconda3\envs\tf-gpu\lib\site-packages\fire\core.py", line 468, in _Fire
    target=component.__name__)
  File "C:\Users\hp\Anaconda3\envs\tf-gpu\lib\site-packages\fire\core.py", line 672, in _CallAndUpdateTrace
    component = fn(*varargs, **kwargs)
  File "C:\Users\hp\Downloads\efficient_densenet_pytorch-master\demo-emotion.py", line 304, in demo
    train(model,train_set1, valid_set=valid_set, test_set=test1, save=save, n_epochs=n_epochs,batch_size=batch_size,seed=seed)
  File "C:\Users\hp\Downloads\efficient_densenet_pytorch-master\demo-emotion.py", line 172, in train
    n_epochs=n_epochs,
  File "C:\Users\hp\Downloads\efficient_densenet_pytorch-master\demo-emotion.py", line 37, in train_epoch
    loader=np.asarray(list(loader))
  File "C:\Users\hp\Anaconda3\envs\tf-gpu\lib\site-packages\torch\utils\data\dataloader.py", line 345, in __next__
    data = self._next_data()
  File "C:\Users\hp\Anaconda3\envs\tf-gpu\lib\site-packages\torch\utils\data\dataloader.py", line 385, in _next_data
    data = self._dataset_fetcher.fetch(index)  # may raise StopIteration
  File "C:\Users\hp\Anaconda3\envs\tf-gpu\lib\site-packages\torch\utils\data\_utils\fetch.py", line 44, in fetch
    data = [self.dataset[idx] for idx in possibly_batched_index]
  File "C:\Users\hp\Anaconda3\envs\tf-gpu\lib\site-packages\torch\utils\data\_utils\fetch.py", line 44, in <listcomp>
    data = [self.dataset[idx] for idx in possibly_batched_index]
  File "C:\Users\hp\Anaconda3\envs\tf-gpu\lib\site-packages\torch\utils\data\dataset.py", line 257, in __getitem__
    return self.dataset[self.indices[idx]]
TypeError: 'DataLoader' object is not subscriptable

代码是：

train_set1 = Owndata()

train1, test1 = train_set1 .get_splits()
# prepare data loaders
train_dl = torch.utils.data.DataLoader(train1, batch_size=32, shuffle=True)
test_dl =torch.utils.data.DataLoader(test1, batch_size=1024, shuffle=False)
test_set1 = Owndata()
'''print('test_set# ',test_set)'''  
if valid_size:
    valid_set = Owndata()
    indices = torch.randperm(len(train_set1))
    train_indices = indices[:len(indices) - valid_size]
    valid_indices = indices[len(indices) - valid_size:]
    train_set1 = torch.utils.data.Subset(train_dl, train_indices)
    valid_set = torch.utils.data.Subset(valid_set, valid_indices)
else:
    valid_set = None
model = DenseNet(
    growth_rate=growth_rate,
    block_config=block_config,
    num_classes=10,
    small_inputs=True,
    efficient=efficient,
)
train(model,train_set1, valid_set=valid_set, test_set=test1, save=save, n_epochs=n_epochs, batch_size=batch_size, seed=seed)

感谢您的帮助！提前谢谢！

Answer 1

不是这行给您一个错误，因为它是您未显示的最后一个train函数。

您正在混淆两件事：

• torch.utils.data.Dataset对象是可索引的（例如，dataset[5]可以正常工作）。这是一个简单的对象，它定义了如何获取单个（通常是单个）数据样本。
• torch.utils.data.DataLoader-不可索引，只能迭代，通常从Dataset以上返回一批数据。可以使用num_workers并行工作。这就是您要索引的内容，而您应该为此使用dataset。

请参阅PyTorch documentation about data，以更好地了解它们的工作原理。