Creating a simple R package

Don’t repeat yourself

Despite the continued (and growing) excitement about R, not everyone is well-versed on creating an R package. Why might this matter? Even if you’re not planning on submitting your code to CRAN or Github for others to see, a good software engineer strives to not repeat themselves. While in C# this means classes, methods, and using statements, in R this means (at a minimum) creating a package. (In a future post we’ll talk object oriented R code.) How does one make a package in R? Here’s a template using RStudio:

Steps toward team-work

1. Click the Project dropdown in the top right of RStudio, select New Directory, and then select a R Package.

2. Set the package name, select its location, and select which .R source files will be a part of it. Click Create Project.

If you need a sample file and function, one can use this (within a file of any name):

squares <‐ function(x) {
  return(x^2)
}

3. Clicking Build and Reload in RStudio builds the new package and loads it into the workspace–this is stated in the console and one can verify this under the Packages tab or by typing search() in the console. Note that Build and Reload also causes the package to appear under R’s library directory.

4. Verify you can call your function by typing (say) squares(5) in the console.

5. To double-check that the package can be called from anywhere, unload the package (mine is called RTesty) using:

detach("package:RTesty", unload=TRUE)

6. Create a sample script in another directory, load the new project, and then make sure your function call works. Using my sample function above, this script was simply:

library(RTesty)
squares(4)

And, of course, the console outputs 16. You’ve just started down a magical journey of code sharability.

Thanks for reading and, remember, don’t repeat yourself!