Ignorant use of "== np.nan" in qlib/data/filter.py

[victor-zou]

🐛 Bug Description

To Reproduce

Remove it or change to np.isnan?

Screenshot

[SunsetWolf]

Hi @victor-zou ,

Thanks for pointing this out — the issue was indeed caused by using == np.nan, which never evaluates to True. We’ve adopted your suggestion and replaced it with np.isnan(...).

A PR has already been submitted to fix this bug. Really appreciate your careful review and helpful feedback!