R语言了解各种R包
This book will guide you from being a user of R packages to being a creator of R
packages. In Chapter 1, Introduction, you’ll learn why mastering this skill is so important,
and why it’s easier than you think. Next, you’ll learn about the basic structure of a
package, and the forms it can take, in Chapter 2, Package Structure. The subsequent
chapters go into more detail about each component. They’re roughly organized in order of
importance:
Chapter 3, R code
The most important directory is R/, where your R code lives. A package with just this
directory is still a useful package. (And indeed, if you stop reading the book after this
chapter, you’ll have still learned some useful new skills.)
Chapter 4, Package Metadata
The DESCRIPTION lets you describe what your package needs to work. If you’re
sharing your package, you’ll also use the DESCRIPTION to describe what it does,
who can use it (the license), and who to contact if things go wrong.
Chapter 5, Object Documentation
If you want other people (including “future you”!) to understand how to use the
functions in your package, you’ll need to document them. I’ll show you how to use
roxygen2 to document your functions. I recommend roxygen2 because it lets you
write code and documentation together while continuing to produce R’s standard
documentation format.
Chapter 6, Vignettes: Long-Form Documentation
Function documentation describes the nitpicky details of every function in your
package. Vignettes give the big picture. They’re long-form documents that show how
to combine multiple parts of your package to solve real problems. I’ll show you how
to use Rmarkdown and knitr to create vignettes with a minimum of fuss.
Chapter 7, Testing
To ensure your package works as designed (and continues to work as you make
changes), it’s essential to write unit tests that define correct behavior, and alert you
when functions break. In this chapter, I’ll teach you how to use the testthat package
to convert the informal interactive tests that you’re already doing to formal,
automated tests.
Chapter 8, Namespace
To play nicely with others, your package needs to define what functions it makes
available to other packages and what functions it requires from other packages. This
is the job of the NAMESPACE file and I’ll show you how to use roxygen2 to generate
it for you. NAMESPACE is one of the more challenging parts of developing an R
package, but it’s critical to master if you want your package to work reliably.
Chapter 9, External Data
The data/ directory allows you to include data with your package. You might do this
to bundle data in a way that’s easy for R users to access, or just to provide compelling
examples in your documentation.
Chapter 10, Compiled Code
R code is designed for human efficiency, not computer efficiency, so it’s useful to
have a tool in your back pocket that allows you to write fast code. The src/ directory
allows you to include speedy compiled C and C++ code to solve performance
bottlenecks in your package.
Chapter 11, Installed Files
You can include arbitrary extra files in the inst/ directory. This is most commonly
used for extra information about how to cite your package, and to provide more
details about copyrights and licenses.
Chapter 12, Other Components
This chapter documents the handful of other components that are rarely needed:
demo/, exec/, po/, and tools/.
The final three chapters describe general best practices not specifically tied to one
directory:
Chapter 13, Git and GitHub
Mastering a version control system is vital for collaborating with others, and is useful
even for solo work because it allows you to easily undo mistakes. In this chapter,
you’ll learn how to use the popular Git and GitHub combo with RStudio.
Chapter 14, Automated Checking
R provides useful automated quality checks in the form of R CMD check. Running
them regularly is a great way to avoid many common mistakes. The results can
sometimes be a bit cryptic, so I provide a comprehensive cheat sheet to help you
convert warnings to actionable insight.
Chapter 15, Releasing a Package
The life cycle of a package culminates with release to the public. This chapter
compares the two main options (CRAN and GitHub) and offers general advice on
managing the process.
