Add taget factory for splitting raster into tiles #76
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Note to self: clean up the tiles files on disk (not in _targets)? Either write them to a tempfile to begin with or add a final target to remove them? (but then won't the files target always be invalidated? hmm...) |
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Ok, it is "working" now (not passing check, but there is a test that should work now to give you an idea of what it does). Here's what the manifest looks like: library(targets)
tar_script({
library(targets)
library(geotargets)
# devtools::load_all()
library(terra)
list(
tar_target(
my_file,
system.file("ex/elev.tif", package="terra"),
format = "file"
),
tar_terra_rast(
my_map,
terra::rast(my_file)
),
tar_terra_tiles(
name = rast_split,
raster = my_map,
template = terra::rast(ncols = 2, nrows = 2),
tiles_dir = "tiles_test"
)
)
})
targets::tar_manifest(callr_function = NULL)
#> terra 1.7.71
#> # A tibble: 5 × 3
#> name command pattern
#> <chr> <chr> <chr>
#> 1 my_file "system.file(\"ex/elev.tif\", package = \"terra\")" <NA>
#> 2 my_map "terra::rast(my_file)" <NA>
#> 3 rast_split_tile "geotargets:::make_tiles(raster = my_map, template =… <NA>
#> 4 rast_split_files "rast_split_tile" map(ra…
#> 5 rast_split "rast(rast_split_files)" map(ra…Created on 2024-05-24 with reprex v2.1.0 |
…akeTiles() is more transparent to user in tar_manifest()
Aariq
changed the title
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I took a shot at creating a
tar_terra_tiles()which is a target factory that creates three targets:yargument ofterra::makeTiles()), splits the raster into tiles, saves them to disk, and returns a vector of file paths.makeTiles()using a target with format = "file" or "file_fast"This downstream target is a pattern that is ready to use in further targets with
pattern = map()and starts to address #74.This is heavily inspired by
tarchetypes::tar_files()The main downside to this pattern is that it basically duplicates the tiles on disk—once saved in a directory defined by the
tiles_dirargument and again in the targets store when those files are read back in. Deleting those files would invalidate the files target, but not the upstream target that creates them, so I'm forced to have the upstream target always re-run withcue = tar_cue("always"). This is not ideal as making tiles is often a computationally expensive step. I've left#TODOcomments with questions and aspirations about how this might work better and would love feedback.