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 calltar_meta()
beforehand and supply it to themeta
argument, then successive calls totar_read()
may run much faster.- store
Character of length 1, path to the
targets
data store. Defaults totar_config_get("store")
, which in turn defaults to_targets/
. When you set this argument, the value oftar_config_get("store")
is temporarily changed for the current function call. Seetar_config_get()
andtar_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.
Storage access
Several functions like tar_make()
, tar_read()
, tar_load()
,
tar_meta()
, and tar_progress()
read or modify
the local data store of the pipeline.
The local data store is in flux while a pipeline is running,
and depending on how distributed computing or cloud computing is set up,
not all targets can even reach it. So please do not call these
functions from inside a target as part of a running
pipeline. The only exception is literate programming
target factories in the tarchetypes
package such as tar_render()
and tar_quarto()
.
Several functions like tar_make()
, tar_read()
, tar_load()
,
tar_meta()
, and tar_progress()
read or modify
the local data store of the pipeline.
The local data store is in flux while a pipeline is running,
and depending on how distributed computing or cloud computing is set up,
not all targets can even reach it. So please do not call these
functions from inside a target as part of a running
pipeline. The only exception is literate programming
target factories in the tarchetypes
package such as tar_render()
and tar_quarto()
.
See also
Other data:
tar_crew()
,
tar_load_everything()
,
tar_load_raw()
,
tar_load()
,
tar_objects()
,
tar_pid()
,
tar_process()
,
tar_read_raw()
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, 1 + 1)), ask = FALSE)
tar_make()
tar_read(x)
})
}