R Packages

An R package is a mechanism for extending the basic functionality of R. It is the natural extension of writing functions that each do a specific thing well. In the previous chapter, we discussed how writing functions abstracts the behavior of a set of R expressions by providing a defined interface, with inputs (i.e. function arguments) and outputs (i.e. return values). The use of functions simplifies things for the user because the user no longer needs to be knowledgeable of the details of the underlying code. They only need to understand the inputs and outputs.

Once one has developed many functions, it becomes natural to group them in to collections of functions that are aimed at achieving an overall goal. This collection of functions can be assembled into an R package. R packages represent another level of abstraction, where the interface presented to the user is a set of user-facing functions. These functions provide access to the underlying functionality of the package and simplify the user experience because the one does not need to be concerned with the many other helper functions that are required.

R packages are a much better way to distribute code to others because they provide a clean and uniform user experience for people who want to interact with your code. R packages require documentation in a standardized format, and the various tools that come with R (and RStudio) help to check your packages so that they do not contain inconsistencies or errors. R users are already familiar with how to use R packages, and so they will be able to quickly adopt your code if is presented in this format.

This chapter highlights the key elements of building R packages. The fine details of building a package can be found in the Writing R Extensions manual.