Where does your R package library live?

You can usually find this out by typing .libPaths() in your R console. If you have an out-of-the-box installation, it will generally be somewhere like:

C:/Program Files/R/R-3.4.2/library

or

/Library/Frameworks/R.framework/Versions/3.4/Resources/library

This is the place on your computer where R will put any packages you attempt to install with install.packages(). However, you might notice one problem: this library is version-specific, which means that when you update R, you will also have to migrate your existing library. Moreover, if you’re on Windows, you may not have permissions to write to the library path 🙀.

What if I told you there was a better way?

The solution to avoid the hassle of constant library migration is to make a custom library folder¹ and set the environmental variable R_LIBS to point to that folder 👍.

Now, this has been touched on before, but when it comes to explaining HOW to set that environment variable, something is always missing² 🤷‍♂️. This short post will demonstrate how to persistently set the variable without ever having to leave R 😎.

Creating your .Renviron file and setting R_LIBS

The .Renviron file is where you can store environment variables that R uses to gather specific information about your particular computer. In this case, we are going to use it to tell R where your R library lives using the R_LIBS environment variable.

What we are going to do is:

1. Create a folder (~/R/library) to serve as our new library
2. Create a file called ~/.Renviron³
3. Add R_LIBS=~/R/library to the ~/.Renviron file
4. Restart R and install our packages.

For this tutorial, I’m using ~/R/library for the custom library, but you can set it to any folder you wish.

The first step, create the directory. Note that this will give you a warning message if the directory already exists.

dir.create("~/R/library", recursive = TRUE)

Now we can create our ~/.Renviron file. This is a part we need to be careful. If there already is a .Renviron file, we don’t want to accidentally clobber it. To help with that, we will use file.exists() with an if statement to tell us whether or not to create the file:

if (file.exists("~/.Renviron")) {
  message("~/.Renviron already exists!")
} else {
  file.create("~/.Renviron")
  message("created ~/.Renviron")
}

## created ~/.Renviron

Now we can write R_LIBS=~/R/library to the ~/.Renviron file:

cat("R_LIBS=~/R/library", file = "~/.Renviron", append = TRUE)

.libPaths()

## [1] "/Users/zhian/R/library"                                        
## [2] "/Library/Frameworks/R.framework/Versions/3.4/Resources/library"

Moving forward

Now you can feel free to update your version of R without having to go through the hassle of migrating your library. Even better, you can take advantage of update.packages() to auto-update packages in your R library like so:

update.packages(ask = FALSE, checkBuilt = TRUE)