I'm going to echo the Insight Data Science Fellowship Program as, by far, the best in that space. Even then, please pick up a copy of Clean Code if you're from another field. That's a chronic issue with data science candidates.
Now also consider that data wrangling is almost always highly coupled to one or more input formats, lots of index-via-literals, string manipulation, type conversions, field copying etc... I think I’d have trouble writing what others would consider Clean code in such a setting - and I’ve programmed for 40 years.