Pandas
It was created by Wes McKinney which is one the best and the most used Python Library. Most of us started our Python journey by installing Pandas.
Unfortunately, a nine years later after creating the library the founder wrote a post were he shared things he hate about pandas. He confess that he didn't follow the best engineering practices when developing the library and the code was ugly.He highlighted them in this post , they are:
- Internals too far from "the metal"
- No support for memory-mapped datasets
- Poor performance in database and file ingest / export
- Warty missing data support