tar_branches {targets}

Reconstruct the branch names and the names of their dependencies.

Description

Given a branching pattern, use available metadata to reconstruct branch names and the names of each branch's dependencies. The metadata of each target must already exist and be consistent with the metadata of the other targets involved.

Usage

tar_branches(name, pattern, store = targets::tar_config_get("store"))

Arguments

name

Symbol, name of the target.

pattern

Language to define branching for a target. For example, in a pipeline with numeric vector targets x and y, tar_target(z, x + y, pattern = map(x, y)) implicitly defines branches of z that each compute x[1] + y[1], x[2] + y[2], and so on. See the user manual for details.

store

Character of length 1, path to the targets data store. Defaults to tar_config_get("store"), which in turn defaults to ⁠_targets/⁠. When you set this argument, the value of tar_config_get("store") is temporarily changed for the current function call. See tar_config_get() and tar_config_set() for details about how to set the data store path persistently for a project.

Details

The results from this function can help you retroactively figure out correspondences between upstream branches and downstream branches. However, it does not always correctly predict what the names of the branches will be after the next run of the pipeline. Dynamic branching happens while the pipeline is running, so we cannot always know what the names of the branches will be in advance (or even how many there will be).

Value

A tibble with one row per branch and one column for each target (including the branched-over targets and the target with the pattern.)

See Also

Other branching: tar_branch_index(), tar_branch_names(), tar_branch_names_raw(), tar_pattern()

Examples

if (identical(Sys.getenv("TAR_EXAMPLES"), "true")) { # for CRAN
tar_dir({ # tar_dir() runs code from a temp dir for CRAN.
tar_script({
  list(
    tar_target(x, seq_len(2)),
    tar_target(y, head(letters, 2)),
    tar_target(z, head(LETTERS, 2)),
    tar_target(dynamic, c(x, y, z), pattern = cross(z, map(x, y)))
  )
}, ask = FALSE)
tar_make()
tar_branches(dynamic, pattern = cross(z, map(x, y)))
})
}