ValueError: Seek before start of file using custom open_with function or S3 file object about fastparquet HOT 3 OPEN

It certainly looks like it ought to work, but can I ask why you are calling it in that manner? For your information, fastparquet does try to guess whether the function passed is actually an fsspec filesystem implementation method, so that must be the difference - you can equally pass fs= in that case.

from fastparquet.

I am working with both pathlib and S3 paths in our pipeline and I want to avoid checking before each call which of the two I have. So I implemented an S3Path analog to pathlib.Path which has a function similar to the one below:

def open(self, *args, **kwargs):
    return S3FileSystem().open(self, *args, **kwargs)

from fastparquet.

I would say this is a genuine bug, and the code deciding what to do with file-like objects versus fsspec-specific files should be revisited. Are you able to do any debugging?

from fastparquet.