Write your own R package

Setting the stage

Slides available on speakerdeck

• What is an R package?
• What is a library?
• Why make an R package?
• How devtools creates a happy workflow.

Prepare your system for package development

System prep and testing

Although we’ll build a very simple package, we’re still going to use the most modern and powerful tools for R package development. In theory, this could eventually involve compiling C/C++ code, which means you need what’s called a build environment. Follow the link above for help preparing your system.

Hands-on activity

In class example that that shows how to

• Create a new R package
• Accept help from devtools and RStudio
• Switch between developing your package package and test driving it
• Document functions and your overall package
• Test your functions
• Depend on another package
• Show off what your package does via a README or a vignette
• Put your package on GitHub to share with the world

In 2016 and 2015, we built the foofactors package, to make the care and feeding of factors less aggravating.

• Write your own R package
• Homework: extend foofactors from where we left off in class.

Resources

Writing R Extensions, the One True Official Document on creating R packages.

R packages from Hadley Wickham. The above lessons follow it and the devtools package workflow quite faithfully. devtools on CRAN, on GitHub.

Hilary Parker’s blog post on the epiphany of writing her first R package

• “I was hit with that familiar feeling of the joy of optimization combined with the regret of past inefficiencies (joygret?). I wish I could go back in time and create the package the first moment I thought about it, and then use all the saved time to watch cat videos because that really would have been more productive.”
• the glorious result: https://github.com/hilaryparker/cats
• see some usage in the R Graph Catalog hint: filter for chapter “other”

Karl Broman’s guide to writing an R package

Karl Broman covers package development in his course Tools for Reproducible Research

Jeff Leek’s guide to writing R packages

Some blog posts accompanying devtools releases highlight useful helper functions for package developers:

• v1.6 October 2014
• v1.8 May 2015
• v1.9.1 September 2015
• The RStudio Package Development with devtools Cheat Sheet is also super helpful. Remember links to the cheat sheets are always available from RStudio Help > Cheatsheets.

Building and Maintaining R Packages with devtools and roxygen2, blog post by Jacob Montgomery and Ryan T. Moore

Writing Package Vignettes, slides for a November 2013 talk by Duncan Murdoch

Roxygen vignette on Generating Rd files

testthat: Get Started with Testing, an article written by Hadley Wickham for The R Journal, Vol. 3/1, June 2011, pp. 5-10. This may no longer be correct in every last detail, due to evolution of testthat, but it still makes an excellent, readable introduction to unit testing in R (packages).

How R Searches and Finds Stuff is a fairly technical blog post for understanding the R search path, but also gives some great explanations on some differences between Imports vs Depends and why Imports is safer.