tar_target_raw() is just like tar_target() except it avoids non-standard evaluation for the arguments: name is a character string, command and pattern are language objects, and there is no tidy_eval argument. Use tar_target_raw() instead of tar_target() if you are creating entire batches of targets programmatically (metaprogramming, static branching).

tar_target_raw(
  name,
  command,
  pattern = NULL,
  packages = targets::tar_option_get("packages"),
  library = targets::tar_option_get("library"),
  deps = NULL,
  string = NULL,
  format = targets::tar_option_get("format"),
  iteration = targets::tar_option_get("iteration"),
  error = targets::tar_option_get("error"),
  memory = targets::tar_option_get("memory"),
  garbage_collection = targets::tar_option_get("garbage_collection"),
  deployment = targets::tar_option_get("deployment"),
  priority = targets::tar_option_get("priority"),
  resources = targets::tar_option_get("resources"),
  storage = targets::tar_option_get("storage"),
  retrieval = targets::tar_option_get("retrieval"),
  cue = targets::tar_option_get("cue")
)

Arguments

name

Character of length 1, name of the target. Subsequent targets can refer to this name symbolically to induce a dependency relationship: e.g. tar_target(downstream_target, f(upstream_target)) is a target named downstream_target which depends on a target upstream_target and a function f(). In addition, a target's name determines its random number generator seed. 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.

command

Similar to the command argument of tar_target() except the object must already be an expression instead of informally quoted code. base::expression() and base::quote() can produce such objects.

pattern

Similar to the pattern argument of tar_target() except the object must already be an expression instead of informally quoted code. base::expression() and base::quote() can produce such objects.

packages

Character vector of packages to load right before the target builds. Use tar_option_set() to set packages globally for all subsequent targets you define.

library

Character vector of library paths to try when loading packages.

deps

Optional character vector of the adjacent upstream dependencies of the target, including targets and global objects. If NULL, dependencies are resolved automatically as usual.

string

Optional string representation of the command. Internally, the string gets hashed to check if the command changed since last run, which helps targets decide whether the target is up to date. External interfaces can take control of string to ignore changes in certain parts of the command. If NULL, the strings is just deparsed from command (default).

format

Optional storage format for the target's return value. With the exception of format = "file", each target gets a file in _targets/objects, and each format is a different way to save and load this file. See the "Storage formats" section for a detailed list of possible data storage formats.

iteration

Character of length 1, name of the iteration mode of the target. Choices:

  • "vector": branching happens with vctrs::vec_slice() and aggregation happens with vctrs::vec_c().

  • "list", branching happens with [[]] and aggregation happens with list().

  • "group": dplyr::group_by()-like functionality to branch over subsets of a data frame. The target's return value must be a data frame with a special tar_group column of consecutive integers from 1 through the number of groups. Each integer designates a group, and a branch is created for each collection of rows in a group. See the tar_group() function to see how you can create the special tar_group column with dplyr::group_by().

error

Character of length 1, what to do if the target runs into an error. If "stop", the whole pipeline stops and throws an error. If "continue", the error is recorded, but the pipeline keeps going. error = "workspace" is just like error = "stop" except targets saves a special workspace file to support interactive debugging outside the pipeline. (Visit https://books.ropensci.org/targets/debugging.html to learn how to debug targets using saved workspaces.)

memory

Character of length 1, memory strategy. If "persistent", the target stays in memory until the end of the pipeline (unless storage is "worker", in which case targets unloads the value from memory right after storing it in order to avoid sending copious data over a network). If "transient", the target gets unloaded after every new target completes. Either way, the target gets automatically loaded into memory whenever another target needs the value. For cloud-based dynamic files such as format = "aws_file", this memory policy applies to temporary local copies of the file in _targets/scratch/": "persistent" means they remain until the end of the pipeline, and "transient" means they get deleted from the file system as soon as possible. The former conserves bandwidth, and the latter conserves local storage.

garbage_collection

Logical, whether to run base::gc() just before the target runs.

deployment

Character of length 1, only relevant to tar_make_clustermq() and tar_make_future(). If "worker", the target builds on a parallel worker. If "main", the target builds on the host machine / process managing the pipeline.

priority

Numeric of length 1 between 0 and 1. Controls which targets get deployed first when multiple competing targets are ready simultaneously. Targets with priorities closer to 1 get built earlier (and polled earlier in tar_make_future()).

resources

Object returned by tar_resources() with optional settings for high-performance computing functionality, alternative data storage formats, and other optional capabilities of targets. See tar_resources() for details.

storage

Character of length 1, only relevant to tar_make_clustermq() and tar_make_future(). If "main", the target's return value is sent back to the host machine and saved locally. If "worker", the worker saves the value.

retrieval

Character of length 1, only relevant to tar_make_clustermq() and tar_make_future(). If "main", the target's dependencies are loaded on the host machine and sent to the worker before the target builds. If "worker", the worker loads the targets dependencies.

cue

An optional object from tar_cue() to customize the rules that decide whether the target is up to date.

Value

A target object. Users should not modify these directly, just feed them to list() in your target script file (default: _targets.R).

See also

Other targets: tar_cue(), tar_target()

Examples

# The following are equivalent. y <- tar_target(y, sqrt(x), pattern = map(x)) y <- tar_target_raw("y", expression(sqrt(x)), expression(map(x))) # Programmatically create a chain of interdependent targets target_list <- lapply(seq_len(4), function(i) { tar_target_raw( letters[i + 1], substitute(do_something(x), env = list(x = as.symbol(letters[i]))) ) }) print(target_list[[1]])
#> <tar_stem> #> name: b #> command: #> do_something(a) #> format: rds #> iteration method: vector #> error mode: stop #> memory mode: persistent #> storage mode: main #> retrieval mode: main #> deployment mode: worker #> priority: 0 #> resources: #> list() #> cue: #> mode: thorough #> command: TRUE #> depend: TRUE #> format: TRUE #> iteration: TRUE #> file: TRUE #> packages: #> targets #> stats #> graphics #> grDevices #> utils #> datasets #> methods #> base #> library: #> NULL
print(target_list[[2]])
#> <tar_stem> #> name: c #> command: #> do_something(b) #> format: rds #> iteration method: vector #> error mode: stop #> memory mode: persistent #> storage mode: main #> retrieval mode: main #> deployment mode: worker #> priority: 0 #> resources: #> list() #> cue: #> mode: thorough #> command: TRUE #> depend: TRUE #> format: TRUE #> iteration: TRUE #> file: TRUE #> packages: #> targets #> stats #> graphics #> grDevices #> utils #> datasets #> methods #> base #> library: #> NULL
if (identical(Sys.getenv("TAR_EXAMPLES"), "true")) { tar_dir({ # tar_dir() runs code from a temporary directory. tar_script(tar_target_raw("x", quote(1 + 1)), ask = FALSE) tar_make() tar_read(x) }) }