Read a target's value from archive storage

Usage

tar_read_archive(
  name,
  package,
  pipeline,
  branches = NULL,
  meta = NULL,
  store = targets::tar_config_get("store")
)

tar_read_archive_raw(
  name,
  package,
  pipeline,
  branches = NULL,
  meta = NULL,
  store = targets::tar_config_get("store")
)

Arguments

name: Name of the target to read. tar_read() expects an unevaluated symbol for the name argument, whereas tar_read_raw() expects a character string.
package: A scalar character of the package name.
pipeline: A scalar character of the pipeline name.
branches: Integer of indices of the branches to load if the target is a pattern.
meta: Data frame of metadata from tar_meta(). tar_read() with the default arguments can be inefficient for large pipelines because all the metadata is stored in a single file. However, if you call tar_meta() beforehand and supply it to the meta argument, then successive calls to tar_read() may run much faster.
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.

Value

The target's return value from its file in _targets/objects/, or the paths to the custom files and directories if format = "file" was set.

Details

tar_read_archive() captures name with non-standard evaluation, whereas tar_read_archive_raw() takes it as a character string.

Examples

# \donttest{
withr::with_envvar(
  c(R_USER_CACHE_DIR = tempfile()),
  {
    tar_make_archive(package = "tarchives", pipeline = "example-model")
    tar_read_archive(model, package = "tarchives", pipeline = "example-model")
  }
)
#> 
#> Call:
#> lm(formula = Sepal.Width ~ Sepal.Length, data = data)
#> 
#> Coefficients:
#>  (Intercept)  Sepal.Length  
#>        1.131         0.278  
#> 
# }