Free Books

Intro

R for Data Science by Garrett Grolemund and Hadley Wickham

Data Viz

ggplot2: Elegant Graphics for Data Analysis by Hadley Wickham
Data Visualization - A practical introduction by Kieran Healy

*down

R Markdown: The Definitive Guide by Yihui Xie, J. J. Allaire, and Garrett Grolemund
blogdown: Creating Websites with R Markdown by Yihui Xie, Amber Thomas, and Alison Presmanes Hill
bookdown: Authoring Books and Technical Documents with R Markdown by Yihui Xie

Statistics

Learning Statistics with R by Danielle Navarro
Introduction to Econometrics with R by Christoph Hanck, Martin Arnold, Alexander Gerber and Martin Schmelzer
An Introduction to Bayesian Thinking by Merlise Clyde et. al.
Statistical Inference via Data Science by Chester Ismay and Albert Y. Kim

Machine Learning

Hands-On Machine Learning with R by Bradley Boehmke & Brandon Greenwell
Feature Engineering and Selection: A Practical Approach for Predictive Models by Max Kuhn and Kjell Johnson

Mapping and Geospatial Analysis

Geocomputation with R by Robin Lovelace, Jakub Nowosad, Jannes Muenchow

Text Analysis

Text Mining with R A Tidy Approach by Julia Silge and David Robinson

Programming

Advanced R by Hadley Wickham
R Packages by Hadley Wickham
Master Spark with R by Javier Luraschi, Kevin Kuo, and Edgar Ruiz
Functional programming and unit testing for data munging with R by Bruno Rodrigues

Websites