Inheriting Settings in Local R Project Profiles

Check it out. You’re starting a beautiful new R package, and you’ve created an .Rprofile file local to that package. For example, you might want to turn off the R language server diagnostics, which can get a bit noisy, and give quite a lot of false positives, when you’re working on a package.

./.Rprofile:

options(
  languageserver.diagnostics = FALSE
)

Great! And now, you try to install your favorite package:

$ Rscript --vanilla -e 'install.packages("tictoc")'

Error in contrib.url(repos, "source") :
trying to use CRAN without setting a mirror
Calls: install.packages -> contrib.url
Execution halted

Hey, what gives!? I definitely told R which CRAN mirror to use. Look at this user-level R profile file here.

~/.Rprofile:

options(
  repos = c(CRAN = "https://cloud.r-project.org/")
)

Oh, yes, R doesn’t automatically merge the two .Rprofile files it finds. And it so happens that it first searches for a project-level config before searching the user-level one. (See the Posit docs for more info.)

Now, my real ~/.Rprofile has some more stuff in it than just that one line, and I don’t really want to have to paste it in to every R project that has some local config. Instead, we can check for the user-level .Rprofile, and if it exists, source it. Something like this:

user_level_profile <- file.path(Sys.getenv("HOME"), ".Rprofile")

if (file.exists(user_level_profile)) {
  source(user_level_profile)
}

(By the way, it’s a good idea to put that at the top of your project-local config. That way, you can override anything that you need to locally.)

Now, if you try to run the Rscript command again, everything will work out fine. (For fun, you can add some cat calls to the ~/.Rprofile and ./.Rprofile to see it in action.)

Note: I believe that Sys.getenv("HOME") works on Windows, but I did not check that!