rprojroot

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.

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)
#> [32m✔[39m Creating
#>   [34m/var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpA7TxJ1/file2afe66d464c/[39m.
#> [32m✔[39m Setting active project to
#>   [34m"/private/var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpA7TxJ1/file2afe66d464c"[39m.
#> [32m✔[39m Creating [34mR/[39m.
#> [32m✔[39m Writing [34mDESCRIPTION[39m.
#> [34mPackage[39m: file2afe66d464c
#> [34mTitle[39m: What the Package Does (One Line, Title Case)
#> [34mVersion[39m: 0.0.0.9000
#> [34mDate[39m: 2024-10-27
#> [34mAuthors@R[39m (parsed):
#>     * Kirill Müller <kirill@cynkra.com> [aut, cre] (<https://orcid.org/0000-0002-1416-3412>)
#> [34mDescription[39m: What the package does (one paragraph).
#> [34mLicense[39m: GPL-3
#> [34mURL[39m: https://github.com/krlmlr/rprojroot,
#>     https://krlmlr.github.io/rprojroot
#> [34mBugReports[39m: https://github.com/krlmlr/rprojroot/issues
#> [34mEncoding[39m: UTF-8
#> [34mRoxygen[39m: list(markdown = TRUE)
#> [34mRoxygenNote[39m: 7.3.2.9000
#> [32m✔[39m Writing [34mNAMESPACE[39m.
#> [32m✔[39m Setting active project to [34m"<no active project>"[39m.

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$find_file()
#> [1] "/private/var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpA7TxJ1/file2afe66d464c"
is_r_package$find_file("tests", "testthat")
#> [1] "/private/var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpA7TxJ1/file2afe66d464c/tests/testthat"

This works identically when starting from a subdirectory:

setwd(file.path(pkg, "R"))
is_r_package$find_file()
#> [1] "/private/var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpA7TxJ1/file2afe66d464c"
is_r_package$find_file("tests", "testthat")
#> [1] "/private/var/folders/dj/yhk9rkx97wn_ykqtnmk18xvc0000gn/T/RtmpA7TxJ1/file2afe66d464c/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/RtmpA7TxJ1/file2afe66d464c/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.