Deprecate using `xlrd` engine in favor of openpyxl

[WillAyd]

xlrd is unmaintained and the previous maintainer has asked us to move towards openpyxl. xlrd works now, but might have some issues when Python 3.9 or later gets released and changes some elements of the XML parser, as default usage right now throws a PendingDeprecationWarning

Considering that I think we need to deprecate using xlrd in favor of openpyxl. We might not necessarily need to remove the former and it does offer some functionality the latter doesn't (namely reading .xls files) but should at the very least start moving towards the latter

[arpit1997]

@WillAyd Should we start with adding openpyxl as an engine in pandas.read_excel.

Happy to contribute a PR for it.

[WillAyd]

It is already available just need to make it default over time, so want to raise a FutureWarning when the user doesn’t explicitly provide an engine that it will change to openpxyl in a future releaae

[jorisvandenbossche]

Would it be an option to simply switch the default, without first raising a warning? Or do the two engines give different results in quite some cases?

Reason I am asking is because if for 99% of the use cases both give exactly the same, raising a warning for all those users feels a bit annoying.

[153957]

The docstrings already require some updating as they currently indicate 'xlrd' is the only option for 'engine'.

[153957]

Would it be an option to simply switch the default, without first raising a warning? Or do the two engines give different results in quite some cases?

It would require installing a different optional package, so a version with deprecation messages/future warnings would be useful.

[WillAyd]

Would it be an option to simply switch the default, without first raising a warning? Or do the two engines give different results in quite some cases?

Reason I am asking is because if for 99% of the use cases both give exactly the same, raising a warning for all those users feels a bit annoying.

Just to add - xlrd is AFAIK the only library that can read the legacy .xls format. From experience even ".xlsx" formats aren't as standardized as you'd hope. The openpyxl reader is pretty new so I guess will see through proper deprecation cycle what differences, if any, arise

[jorisvandenbossche]

Just to add - xlrd is AFAIK the only library that can read the legacy .xls format.

And to be clear, for those the default would stay xlrd, and this would not be deprecated, right?

So the question about "switching the default" was only for xlsx files.

[WillAyd]

Up for debate but for that I think we want to push people towards reading .xlsx files. xlrd is not maintained any more and might break with Python 3.9, so would want to get ahead of that as much as possible

[Hiyorimi]

So what is the decision ?

Dump xlrd disregarding .xls support and to replace it with openpyxl ?

[WillAyd]

We need to deprecate using xlrd by default. I think it's fine to do for all extensions, including .xls - interesting in a PR?

[GallowayJ]

Hi @WillAyd I'm interested in working on this. Is the decision to just raise a FutureWarning for all extensions when no engine is explicitly provided by the user?