targets (version 0.4.1)

tar_meta: Read a project's metadata.

Description

Read the metadata of all recorded targets and global objects.

Usage

tar_meta(
  names = NULL,
  fields = NULL,
  targets_only = FALSE,
  complete_only = FALSE
)

Arguments

names

Optional, names of the targets. If supplied, tar_meta() only returns metadata on these targets. You can supply symbols, a character vector, or tidyselect helpers like starts_with(). If NULL, all names are selected.

fields

Optional, names of columns/fields to select. If supplied, tar_meta() only returns the selected metadata columns. If NULL, all fields are selected. You can supply symbols, a character vector, or tidyselect helpers like starts_with(). The name column is always included first no matter what you select. Choices:

• name: name of the target or global object.

• type: type of the object: either "function" or "object" for imported global objects, and "stem", "branch", "map", or "cross" for targets.

• data: hash of the output data.

• command: hash of the target's deparsed command.

• depend: hash of the immediate upstream dependencies of the target.

• seed: random number generator seed with which the target was built. A target's random number generator seed is a deterministic function of its name. In this way, each target runs with a reproducible seed so someone else running the same pipeline should get the same results, and no two targets in the same pipeline share the same seed. (Even dynamic branches have different names and thus different seeds.) You can recover the seed of a completed target with tar_meta(your_target, seed) and run set.seed() on the result to locally recreate the target's initial RNG state.

• path: A list column of paths to target data. Usually, each element is a single path, but there could be multiple paths per target for dynamic files (i.e. tar_target(format = "file")).

• time: POSIXct object with the time the target's data in storage was last modified. Displayed in the current time zone of the system. If there are multiple outputs for that target, as with file targets, then the maximum time is shown. Only time stamps of actual targets are recorded (not functions or other global objects). No time stamp is recorded for URL targets because not all URLs have a "last-modified" time, and the ones that do have times do not necessarily adhere to a standardized format that targets can interpret. For the latest time stamp of a URL, use tar_timestamp() and specify the POSIX format and time zone that the website uses.

• size: hash of the sum of all the bytes of the files at path.

• bytes: total file size in bytes of all files in path.

• format: character, one of the admissible data storage formats. See the format argument in the tar_target() help file for details.

• iteration: character, either "list" or "vector" to describe the iteration and aggregation mode of the target. See the iteration argument in the tar_target() help file for details.

• parent: for branches, name of the parent pattern.

• children: list column, names of the children of targets that have them. These include buds of stems and branches of patterns.

• seconds: number of seconds it took to run the target.

• warnings: character string of warning messages from the last run of the target.

• error: character string of the error message if the target errored.

targets_only

Logical, whether to just show information about targets or also return metadata on functions and other global objects.

complete_only

Logical, whether to return only complete rows (no NA values).

Value

A data frame with one row per target/object and the selected fields.

Details

A metadata row only updates when the target is built. tar_progress() shows information on targets that are running. That is why the number of branches may disagree between tar_meta() and tar_progress() for actively running pipelines.

See Also

Other data: tar_load_raw(), tar_load(), tar_objects(), tar_pid(), tar_process(), tar_read_raw(), tar_read()

Examples

# NOT RUN {
if (identical(Sys.getenv("TAR_LONG_EXAMPLES"), "true")) {
tar_dir({ # tar_dir() runs code from a temporary directory.
tar_script({
  list(
    tar_target(x, seq_len(2)),
    tar_target(y, 2 * x, pattern = map(x))
  )
}, ask = FALSE)
tar_make()
tar_meta()
tar_meta(starts_with("y_"))
})
}
# }