tar_cue_age {tarchetypes}

Cue to run a target when the last output reaches a certain age

Description

tar_cue_age() creates a cue object to rerun a target if the most recent output data becomes old enough. The age of the target is determined by targets::tar_timestamp(), and the way the time stamp is calculated is explained in the Details section of the help file of that function.

Usage

tar_cue_age(
  name,
  age,
  command = TRUE,
  depend = TRUE,
  format = TRUE,
  repository = TRUE,
  iteration = TRUE,
  file = TRUE
)

Arguments

name

Symbol, name of the target.

age

A difftime object of length 1, such as as.difftime(3, units = "days"). If the target's output data files are older than age (according to the most recent time stamp over all the target's output files) then the target will rerun. On the other hand, if at least one data file is younger than Sys.time() - age, then the ordinary invalidation rules apply, and the target may or not rerun. If you want to force the target to run every 3 days, for example, set age = as.difftime(3, units = "days").

command

Logical, whether to rerun the target if command changed since last time.

depend

Logical, whether to rerun the target if the value of one of the dependencies changed.

format

Logical, whether to rerun the target if the user-specified storage format changed. The storage format is user-specified through tar_target() or tar_option_set().

repository

Logical, whether to rerun the target if the user-specified storage repository changed. The storage repository is user-specified through tar_target() or tar_option_set().

iteration

Logical, whether to rerun the target if the user-specified iteration method changed. The iteration method is user-specified through tar_target() or tar_option_set().

file

Logical, whether to rerun the target if the file(s) with the return value changed or at least one is missing.

Details

tar_cue_age() uses the time stamps from tar_meta()$time. If no time stamp is recorded, the cue defaults to the ordinary invalidation rules (i.e. mode = "thorough" in targets::tar_cue()).

Value

A cue object. See the "Cue objects" section for background.

Dynamic branches at regular time intervals

Time stamps are not recorded for whole dynamic targets, so tar_age() is not a good fit for dynamic branching. To invalidate dynamic branches at regular intervals, it is recommended to use targets::tar_older() in combination with targets::tar_invalidate() right before calling tar_make(). For example, tar_invalidate(any_of(tar_older(Sys.time - as.difftime(1, units = "weeks")))) # nolint invalidates all targets more than a week old. Then, the next tar_make() will rerun those targets.

Cue objects

A cue object is an object generated by targets::tar_cue(), tarchetypes::tar_cue_force(), or similar. It is a collection of decision rules that decide when a target is invalidated/outdated (e.g. when tar_make() or similar reruns the target). You can supply these cue objects to the tar_target() function or similar. For example, tar_target(x, run_stuff(), cue = tar_cue(mode = "always")) is a target that always calls run_stuff() during tar_make() and always shows as invalidated/outdated in tar_outdated(), tar_visnetwork(), and similar functions.

See Also

Other cues: tar_age(), tar_cue_age_raw(), tar_cue_force(), tar_cue_skip()

Examples

if (identical(Sys.getenv("TAR_LONG_EXAMPLES"), "true")) {
targets::tar_dir({ # tar_dir() runs code from a temporary directory.
targets::tar_script({
  library(tarchetypes)
  list(
    targets::tar_target(
      data,
      data.frame(x = seq_len(26)),
      cue = tarchetypes::tar_cue_age(
        name = data,
        age = as.difftime(0.5, units = "secs")
      )
    )
  )
})
targets::tar_make()
Sys.sleep(0.6)
targets::tar_make()
})
}