This package helps accessing files relative to a project root to stop the working directory insanity. It is a low-level helper package for the here package.

library(rprojroot)

Example

The rprojroot package works best when you have a “project”: all related files contained in a subdirectory that can be categorized using a strict criterion. Let’s create a package for demonstration.

dir <- tempfile()
pkg <- usethis::create_package(dir)
#> ✔ Creating
#>   /var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpVBhMLR/file337b29a46586/.
#> ✔ Setting active project to
#>   "/private/var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpVBhMLR/file337b29a46586".
#> ✔ Creating R/.
#> ✔ Writing DESCRIPTION.
#> Package: file337b29a46586
#> Title: What the Package Does (One Line, Title Case)
#> Version: 0.0.0.9000
#> Date: 2025-06-27
#> Authors@R (parsed):
#>     * Kirill Müller <kirill@cynkra.com> [aut, cre] (<https://orcid.org/0000-0002-1416-3412>)
#> Description: What the package does (one paragraph).
#> License: MIT
#> URL: https://github.com/krlmlr/rprojroot,
#>     https://krlmlr.github.io/rprojroot
#> BugReports: https://github.com/krlmlr/rprojroot/issues
#> Encoding: UTF-8
#> Roxygen: list(markdown = TRUE)
#> RoxygenNote: 7.3.2.9000
#> ✔ Writing NAMESPACE.
#> ✔ Setting active project to "<no active project>".

R packages satisfy the is_r_package criterion. A criterion is an object that contains a find_file() function. With pkg as working directory, the function works like file.path(), rooted at the working directory:

setwd(pkg)
is_r_package
#> Root criterion: contains a file "DESCRIPTION" with contents matching "^Package: "
is_r_package$find_file()
#> [1] "/private/var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpVBhMLR/file337b29a46586"
is_r_package$find_file("tests", "testthat")
#> [1] "/private/var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpVBhMLR/file337b29a46586/tests/testthat"

This works identically when starting from a subdirectory:

setwd(file.path(pkg, "R"))
is_r_package$find_file()
#> [1] "/private/var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpVBhMLR/file337b29a46586"
is_r_package$find_file("tests", "testthat")
#> [1] "/private/var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpVBhMLR/file337b29a46586/tests/testthat"

There is one exception: if the first component passed to find_file() is already an absolute path. This allows safely applying this function to paths that may be absolute or relative:

setwd(file.path(pkg, "R"))
path <- is_r_package$find_file()
is_r_package$find_file(path, "tests", "testthat")
#> [1] "/private/var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpVBhMLR/file337b29a46586/tests/testthat"

As long as you are sure that your working directory is somewhere inside your project, you can retrieve the project root.

Installation and further reading

Install the package from CRAN:

install.package("rprojroot")

See the documentation for more detail.

Code of Conduct

Please note that the rprojroot project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.