String as input in petastorm dataloaders

[freud14-tm]

In the _sanitize_pytorch_types function used in petastorm dataloaders, an exception is raised when an input is a string:

petastorm/petastorm/pytorch.py

Line 64 in 0b0775a

elif re.search('[SaUO]', value.dtype.str):

Is this really necessary? Maybe the default_collate function from PyTorch might not always like, although it seems to support it according to the documentation, but this prevents making other types of collate functions.

Would you consider removing the exception? Thank you.

[selitvin]

Sure! Would you like to propose a PR for that? Ideally, with a small unit test showing that it works.

[freud14-tm]

It seems more complicated than I thought with the current code base of the library and I am not using the library right now. Still think the idea is worthwhile but feel free to close the issue if you wish. Otherwise, let it open in order to keep the idea close.

[pratikgujjar]

Wondering if there is a reason for the string type to not be supported? A column in a parquet file could be all string labels. It is currently not possible to read this parquet file as a PyTorch dataloader becuase this line in the code.