When shuffle is True for DataLoader what is the default Sampler?

nlp
1

When shuffle is True for DataLoader class what is the default Sampler then?
From the docs:

shuffle (bool, optional): set to ``True`` to have the data reshuffled
            at every epoch (default: ``False``).

If I don’t set the Sampler one must be used by default. Can you give any clue?

2

If no sampler was specified and shuffle=True, the RandomSampler will be used as shown in this line of code.

3

Thanks, from there I also saw one interesting line
if batch_sampler is None:

So if we set the batch_sampler=bs where bs is instance of the class BatchSampler we are OK?

So I guess if we do have batch_size greater than 1 for our DataLoader it is more common to use the BatchSampler?

4

Yes, if no batch_sampler was provided, the sampler (either default or passed) will be wrapped in a BatchSampler instance.

5

@ptrblck if i dont give sampler and shuffle is also false.
How are items retrieved by dataloader.

6

Using the SequentialSampler as shown in this line, a couple lines below the above. You can find more information about it at https://pytorch.org/docs/stable/data.html#torch.utils.data.SequentialSampler

7

Thanks I use that but dont know why i get an error