Learning a computer language like R can be either frustrating, fun, or boring. Having fun requires challenges that wake up the learner’s curiosity but also provide an emotional reward on overcoming them. This book is designed so that it includes smaller and bigger challenges, in what I call playgrounds, in the hope that all readers will enjoy their path to R fluency. Fluency in the use of a language is a skill that is acquired through practice and exploration. Although rarely mentioned separately, fluency in a computer programming language involves both writing and reading. The parallels between natural and computer languages are many, but differences are also important. For students and professionals in the biological sciences, humanities, and many applied fields, recognizing the parallels between R and natural languages should help them feel at home with R. The approach I use is similar to that of a travel guide, encouraging exploration and describing the available alternatives and how to reach them. The intention is to guide the reader through the R landscape of 2020 and beyond.

• R as it is currently used
• Few prescriptive rules—mostly the author’s preferences together with alternatives
• Explanation of the R grammar emphasizing the "R way of doing things"
• Tutoring for "programming in the small" using scripts
• The grammar of graphics and the grammar of data described as grammars
• Examples of data exchange between R and the foreign world using common file formats
• Coaching for becoming an independent R user, capable of both writing original code and solving future challenges

• Tries to break the ice and help readers from all disciplines feel at home with R
• Does not make assumptions about what the reader will use R for
• Attempts to do only one thing well: guide readers into becoming fluent in the R language

Pedro J. Aphalo is a PhD graduate from the University of Edinburgh, and is currently a lecturer at the University of Helsinki. A plant biologist and agriculture scientist with a passion for data, electronics, computers, and photography, in addition to plants, Dr. Aphalo has been a user of R for 25 years. He first organized an R course for MSc students 18 years ago, and is the author of 13 R packages currently in CRAN.