Hearing/reading the same thing again and again in different ways help to properly deepen understanding and solidify material. With every repetition, more and more gaps are filled in the overall understanding and the creative potential to combine elements improves.
Basics
- Hands-On Programming with R by Garrett Grolemund
- Introduction to R
- R for Data Science by Hadley Wickham and Garrett Grolemund
- Advanced R by Hadley Wickham
- R packages by Hadley Wickham
- Introduction to Spatial Data Programming with R by Michael Dorman