- R for Data Science : Hadley Wickham and Garrett Grolemund have written this amazing resources on using R. Most of the chapters are based on packages developed by Hadley.
- R Graphic Cookbook : The book is very useful for learning the ggplot2 package in R. The book is freely available online and has many useful tips and recipes for creating visualizations in R.
- Tidy Text Mining in R : A free book on text mining in R.
- Elements of Statistical Learning : A great way to get acquainted to Machine Learning.
- Interactive Data Visualization (D3) : A great way to get started on learning D3. The book is free to read online.
- Networks : A free online book for learning Network Science.
- Journal of Economic Perspective : All the articles on this website are freely downloadable. Almost all articles have data sets and code for replication.
- 100 free data science books : Has a very good collection of data science books , not just limited to R.