Read a target's value from storage.

Read a target's return value from its file in _targets/objects/. For dynamic files (i.e. format = "file") the paths are returned.

Usage

tar_read(
  name,
  branches = NULL,
  meta = tar_meta(store = store),
  store = targets::tar_config_get("store")
)

Arguments

name

Symbol, name of the target to read.

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.

Limited scope

tar_read() and tar_load() are only for exploratory analysis and literate programming, and tar_read_raw() and tar_load_raw() are only for exploratory analysis. targets automatically loads the correct dependencies into memory when the pipeline is running, so invoking these functions from inside a target is rarely advisable.

See also

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

Examples

if (identical(Sys.getenv("TAR_EXAMPLES"), "true")) {
tar_dir({ # tar_dir() runs code from a temporary directory.
tar_script(list(tar_target(x, 1 + 1)), ask = FALSE)
tar_make()
tar_read(x)
})
}