ENH: merge_asof with "how” functionality

[SterArcher]

Feature Type

• [ ] Adding new functionality to pandas

• [X] Changing existing functionality in pandas

• [ ] Removing existing functionality in pandas

Problem Description

Hi, i have a problem when merge_asof is the perfect method, but it returns error when there are missing values in left data frame.

ValueError: Merge keys contain null values on left side

The classic merge function already has this option, where you can specify inner, outer.

Thank you!

Feature Description

I would recommend to add "how" parameter to merge_asof function.

Alternative Solutions

Na

Additional Context

https://stackoverflow.com/questions/64723478/do-full-outer-join-with-pandas-merge-asof/64723601#64723601

https://github.com/pandas-dev/pandas/issues/23189#issue-370772961