That's good you got exposure to Python (and, I assume, numpy/scipy/pandas etc.), and you're already familiar with R. Are you majoring in data science, and just looking for something extra?

If you're interested in machine learning, Andrew Ng Coursera course is almost a right of passage at this point - it's very accessible: https://www.coursera.org/learn/machine-learning

Kutner is the bible on regression models (tho, not a super fun read): https://www.amazon.com/dp/0073014664

This was one of my favorites as an undergrad: https://www.amazon.com/gp/product/0805833889