I have now been programming in R for over 15 years, and have been doing it full-time for the last five years. This has given me the luxury of time to examine how the language works. This book is my attempt to pass on what I’ve learned so that you can understand the intricacies of R as quickly and painlessly as possible. Reading it will help you avoid the mistakes I’ve made and dead ends I’ve gone down, and will teach you useful tools, techniques, and idioms that can help you to attack many types of problems. In the process, I hope to show that, despite its sometimes frustrating quirks, R is, at its heart, an elegant and beautiful language, well tailored for data science.