Beyond Basics in R
https://github.com/dsidavis/RBeyondBasics
This series of workshops aims to get you beyond the basics. We deliberately don't call it "Advanced R". "Advanced" suggests it is for the elite R users, the "1%". My firm belief is that the material we cover here is for any R user that uses R regularly, i.e. more than a once-off interaction.
My premise is simple. If you will be using R (or any general purpose proramming language or software system) for a year or more of your career, then you are better off learning how to use it properly. It will save time in the long run and make you much more productive. In particular, you can focus on the real problems, not the annoying programming problems.