Attention

June 2024 Status Update: Removing DataPipes and DataLoader V2

We are re-focusing the torchdata repo to be an iterative enhancement of torch.utils.data.DataLoader. We do not plan on continuing development or maintaining the [DataPipes] and [DataLoaderV2] solutions, and they will be removed from the torchdata repo. We’ll also be revisiting the DataPipes references in pytorch/pytorch. In release torchdata==0.8.0 (July 2024) they will be marked as deprecated, and in 0.9.0 (Oct 2024) they will be deleted. Existing users are advised to pin to torchdata==0.8.0 or an older version until they are able to migrate away. Subsequent releases will not include DataPipes or DataLoaderV2. Please reach out if you suggestions or comments (please use this issue for feedback)

HashChecker

class torchdata.datapipes.iter.HashChecker(source_datapipe: IterDataPipe[Tuple[str, IOBase]], hash_dict: Dict[str, str], hash_type: str = 'sha256', rewind: bool = True)

Computes and checks the hash of each file, from an input DataPipe of tuples of file name and data/stream (functional name: check_hash). If the hashes match the given hash in the dictionary, it yields a tuple of file name and data/stream. Otherwise, it will raise an error.

Parameters:

• source_datapipe – IterDataPipe with tuples of file name and data/stream

• hash_dict – Dictionary that maps file names to their corresponding hashes

• hash_type – The type of hash function to apply

• rewind – Rewind the stream after using the stream to compute the hash (this does not work with non-seekable stream, e.g. HTTP)

Example

>>> from torchdata.datapipes.iter import IterableWrapper, FileOpener
>>> expected_MD5_hash = "bb9675028dd39d2dd2bf71002b93e66c"
File is from "https://raw.githubusercontent.com/pytorch/data/main/LICENSE"
>>> file_dp = FileOpener(IterableWrapper(["LICENSE.txt"]), mode='rb')
>>> # An exception is only raised when the hash doesn't match, otherwise (path, stream) is returned
>>> check_hash_dp = file_dp.check_hash({"LICENSE.txt": expected_MD5_hash}, "md5", rewind=True)
>>> reader_dp = check_hash_dp.readlines()
>>> it = iter(reader_dp)
>>> path, line = next(it)
>>> path
LICENSE.txt
>>> line
b'BSD 3-Clause License'