The following books, which I have found useful, either provide a broad introduction to the R programming language, or a more targeted coverage of a particular application. The texts published by O'Reilly have on-line versions made available for free; there entries here provide links to the on-line versions.
- Chambers, J. M. Software for Data Analysis: Programming with R, Springer: New York, 2008.
- Chang, W. R Graphics Cookbook, O'Reilly, 2013.
- Gardner, M. Beginning R: The Statistical Programming Language, Wiley, 2012.
- Gillespie, C.; Lovelace, R. Efficient R Programming, O'Reilly, 2020.
- Grolemund, G. Hands-On Programming with R, O'Reilly, 2014.
- Horton, N. J.; Kleinman, K. Using R and RStudio for Data Management, Statistical Analysis, and Graphics, 2nd Edition, CRC Press, 2015.
- James, G.; Witten, D.; Hastie, T.; Tibshirani, R. An Introduction to Statistical Learning with Applications in R, Springer, 2013.
- Lander, J. P. R for Everyone: Advanced Analytics and Graphics, Addison Wesley, 2014.
- Kabacoff, Robert I. R in Action: Data Analysis and Graphics with R, Manning, 2011.
- Maindonald, J.; Braun, J. Data Analysis and Graphics Using R, Cambridge University Press: Cambridge, UK, 2003.
- Matloff, N. The Art of R Programming, No Starch Press, 2011.
- Sarkar, D. Lattice: Multivariate Data Visualization With R, Springer: New York, 2008.
- Vaughn, S. Scientific Inference, Cambridge, 2013.
- Wickham, H. ggplot2, Springer, 2009.
- Wickham, H.; Grolemund, G. R for Data Science, O'Reilly, 2017.
- Doi, J.; Potter, G.; Wong, J. "Web Application Teaching Tools for Statistics Using R and Shiny", Technology Innovations in Statistics Education, 2016, 9.
- CRANberries (http://dirk.eddelbuettel.com/cranberries/)
- The R Project for Statistical Computing (https://www.r-project.org/)
- The R Graph Gallery (http://www.r-graph-gallery.com/)
- R-Bloggers (https://www.r-bloggers.com/)
- RStudio (https://www.rstudio.com/products/rstudio/)
- RStudio Packages (https://www.rstudio.com/products/rpackages/)
- RWeekly (https://rweekly.org/)
- Stackoverflow (https://stackoverflow.com/questions/tagged/r)