Write a helper R script.

Source: R/tar_helper.R, R/tar_helper_raw.R

Write a helper R script for a targets pipeline. Could be supporting functions or the target script file (default: _targets.R) itself.

tar_helper() expects an unevaluated expression for the code argument, whereas tar_helper_raw() expects an evaluated expression object.

tar_helper(path = NULL, code = NULL, tidy_eval = TRUE, envir = parent.frame())

tar_helper_raw(path = NULL, code = NULL)

Arguments

path

Character of length 1, path to write (or overwrite) code. If the parent directory does not exist, tar_helper_raw() creates it. tar_helper() overwrites the file if it already exists.

code

Code to write to path. tar_helper() expects an unevaluated expression for the code argument, whereas tar_helper_raw() expects an evaluated expression object.

tidy_eval

Logical, whether to use tidy evaluation on code. If turned on, you can substitute expressions and symbols using !! and !!!. See examples below.

envir

Environment for tidy evaluation.

Value

NULL (invisibly)

Details

tar_helper() is a specialized version of tar_script() with flexible paths and tidy evaluation.

See also

Other scripts: tar_edit(), tar_github_actions(), tar_renv(), tar_script()

Examples

# Without tidy evaluation:
path <- tempfile()
tar_helper(path, code = x <- 1)
tar_helper_raw(path, code = quote(x <- 1)) # equivalent
writeLines(readLines(path))
#> x <- 1
# With tidy evaluation:
y <- 123
tar_helper(path, x <- !!y)
writeLines(readLines(path))
#> x <- 123