In r-lib/here: A Simpler Way to Find Your Files

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  error = !identical(Sys.getenv("IN_PKGDOWN"), "true")
)

project_path <- system.file("demo-project", package = "here")

The here package enables easy file referencing by using the top-level directory of a file project to easily build file paths. This article demonstrates the case where the working directory is set to a subdirectory of the project root, for instance when rendering an R Markdown document that lives in a subdirectory. See vignette("here") for a more general introduction.

rmarkdown starts in a subdirectory

For demonstration, this article uses a data analysis project that lives in `r project_path` on my machine. This is the project root. The path will most likely be different on your machine, the here package helps deal with this situation.

The project has the following structure:

fs::dir_tree(project_path)

When report.Rmd is rendered, the working directory is internally set to <project root>/analysis by rmarkdown:

setwd(file.path(project_path, "analysis"))

knitr::opts_knit$set(root.dir = file.path(project_path, "analysis"))

getwd()

However, penguins.csv still lives in the data/ subdirectory. The report requires the penguins.csv file to work.

here always uses project-relative paths

To render report.Rmd, you would have to ensure the path to penguins.csv is relative to the analysis/ directory - i.e., ../data/penguins.csv. The chunks would knit properly, but could not be run in the console since the working directory in the console isn't analysis/.

The here package circumvents this issue by always referring to the project root:

here::i_am("analysis/report.Rmd")

All files accessed by report.Rmd should be referred to using here():

library(here)
here("data", "penguins.csv")
here("data/penguins.csv")

This ensures that penguins.csv can be read both when the report is knit and when the code is run interactively in the console.

r-lib/here documentation built on Dec. 11, 2024, 10:33 p.m.