tar_terra_vrt {geotargets} | R Documentation |
Create a GDAL Virtual Dataset (VRT) with terra
Description
Provides a target format for terra::SpatRaster, terra::SpatRasterDataset, and terra::SpatRasterCollection objects representing a GDAL Virtual Dataset (VRT).
Usage
tar_terra_vrt(
name,
command,
pattern = NULL,
...,
tidy_eval = targets::tar_option_get("tidy_eval"),
packages = targets::tar_option_get("packages"),
library = targets::tar_option_get("library"),
repository = targets::tar_option_get("repository"),
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"),
description = targets::tar_option_get("description")
)
Arguments
name |
Symbol, name of the target.
In A target name must be a valid name for a symbol in R, and it
must not start with a dot. Subsequent targets
can refer to this name symbolically to induce a dependency relationship:
e.g. In most cases, The target name is the name of its local data file in storage. Some file systems are not case sensitive, which means converting a name to a different case may overwrite a different target. Please ensure all target names have unique names when converted to lower case. 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 |
command |
R code to run the target.
In |
pattern |
Code to define a dynamic branching branching for a target.
In To demonstrate dynamic branching patterns, suppose we have
a pipeline with numeric vector targets |
... |
Additional arguments passed to |
tidy_eval |
Logical, whether to enable tidy evaluation
when interpreting |
packages |
Character vector of packages to load right before
the target runs or the output data is reloaded for
downstream targets. Use |
library |
Character vector of library paths to try
when loading |
repository |
Character of length 1, remote repository for target storage. Choices:
Note: if |
error |
Character of length 1, what to do if the target stops and throws an error. Options:
|
memory |
Character of length 1, memory strategy. Possible values:
For cloud-based file targets
(e.g. |
garbage_collection |
Logical: |
deployment |
Character of length 1. If |
priority |
Deprecated on 2025-04-08 ( |
resources |
Object returned by |
storage |
Character string to control when the output of the target
is saved to storage. Only relevant when using
|
retrieval |
Character string to control when the current target
loads its dependencies into memory before running.
(Here, a "dependency" is another target upstream that the current one
depends on.) Only relevant when using
|
cue |
An optional object from |
description |
Character of length 1, a custom free-form human-readable
text description of the target. Descriptions appear as target labels
in functions like |
Details
tar_terra_vrt()
accepts SpatRaster, SpatRasterDataset, or
SpatRasterCollection objects as input, and returns a SpatRaster referencing
a GDAL Virtual Dataset file (.vrt). The .vrt file format uses XML and
describes the layers and tiles that comprise a virtual raster data source.
To use a list of SpatRaster of varying extent, such as output from
tar_terra_tiles()
, or a character vector of paths, wrap the tile result
in a call to terra::sprc()
to create a SpatRasterCollection.
Value
target class "tar_stem" for use in a target pipeline
See Also
Examples
if (Sys.getenv("TAR_LONG_EXAMPLES") == "true") {
targets::tar_dir({ # tar_dir() runs code from a temporary directory.
targets::tar_script({
list(
geotargets::tar_terra_vrt(
terra_rast_example,
terra::rast(system.file("ex/elev.tif", package = "terra"))
)
)
})
targets::tar_make()
x <- targets::tar_read(terra_rast_example)
})
targets::tar_dir({
targets::tar_script({
library(targets)
library(geotargets)
list(
tar_terra_rast(r, terra::rast(
system.file("ex", "elev.tif", package = "terra")
)),
tar_terra_rast(r2, r * 2),
tar_terra_tiles(rt, c(r, r2), function(x)
tile_grid(x, ncol = 2, nrow = 2)),
tar_terra_vrt(r3, terra::sprc(rt))
)
})
})
}