Hadley Wickham and Jenny Bryan - R Packages 2E: Organize, Test, Document, and Share Your Code (for True Epub)

• 2023-04-17: First Release

Welcome to R packages by Hadley Wickham and Jennifer Bryan. Packages are the fundamental units of reproducible R code. They include reusable R functions, the documentation that describes how to use them, and sample data. In this book youll learn how to turn your code into packages that others can easily download and use. Writing a package can seem overwhelming at first. So start with the basics and improve it over time. It doesnt matter if your first version isnt perfect as long as the next version is better.

This is the work-in-progress 2nd edition of the book.

Welcome to the 2nd edition of R Packages! If youre familiar with the 1st edition, this preface describes the major changes so that you can focus your reading on the new areas.

There are several main goals for this edition:

• Update to reflect changes in the devtools package, specifically, its conscious uncoupling into a set of smaller, more focused packages.

• Expand coverage of workflow and process, alongside the presentation of all the important moving parts that make up an R package.

• Cover entirely new topics, such as package websites and GitHub Actions.

All content has been completely revised and updated. Many chapters are new or re-organized and a couple have been removed:

• New , The Whole Game, previews the entire package development process.

• New , System setup, has been carved out of the previous Introduction and gained more detail.

• The chapter formerly known as Package structure has been expanded and split into two chapters, one covering package structure and state ().

• New , The package within, demonstrates how to extract reusable logic out of data analysis scripts and into a package.

• The sections Organising your functions and Code style, from which can automatically apply many of the rules.

• The coverage of testing has expanded into three chapters: for various advanced topics.

• Material around the NAMESPACE file and dependency relationships has been re-organized into two chapters: gives practice instructions for using different types of dependencies in different settings.

• New , Licensing, expands earlier content on licensing into its own chapter.

• The chapter on C/C++ has been removed. It didnt have quite enough information to be useful, and since the first edition of the book, other resources have arisen that are better learning resources.

• The Other components chapter has been removed.

• The chapter on Git/GitHub has been reframed around the more general topic of software development practices (.

• The very short inst chapter has been combined into , with all the other directories that can be important in specific contexts, but that arent mission critical to all packages.

The following typographical conventions are used in this book:

Indicates new terms, URLs, email addresses, filenames, and file extensions.

Used for program listings, as well as within paragraphs to refer to program elements such as variable or function names, databases, data types, environment variables, statements, and keywords.

Shows commands or other text that should be typed literally by the user.

Shows text that should be replaced with user-supplied values or by values determined by context.