Fold plan from k-fold Nearest Neighbour Distance Matching.

Usage

knndm_folds(
  meta,
  k = 5L,
  predpoints = NULL,
  test_ids = NULL,
  hold_out_test = FALSE,
  crs = 4326,
  project_to = "+proj=moll +lon_0=0 +datum=WGS84 +units=m",
  seed = 42L,
  calibration_ids = NULL,
  hold_out_calibration = FALSE,
  ...
)

Arguments

meta: Store metadata: needs x, y and sample_id.
k: Number of folds.
predpoints: Where the map will be predicted: a data frame with x and y, or an sf object. REQUIRED unless modeldomain is passed through ... – the method has no meaning without it, so it is not defaulted.
test_ids: Frozen test sample_ids. Preferred over hold_out_test whenever several plans are to be compared on the same held-out data.
hold_out_test: Carve a test set by running kNNDM with k + 1 folds and holding one out. FALSE by default: a test set that changes with k is not a frozen test set.
crs: CRS of meta$x/meta$y. 4326 by default.
project_to: Projection used for the distance comparison, or NULL to use the coordinates as they are (correct only if already projected).
seed: Seed, for the sampling kNNDM does internally.
calibration_ids: Frozen calibration-set sample_ids, as test_ids.
hold_out_calibration: Carve a calibration set for the intervals as the test set is carved: kNNDM in k + 1 folds over what the test left, one held out. FALSE by default.
...: Passed to CAST::knndm() – maxp, clustering, samplesize, modeldomain, space.

Value

A fold_plan.

Examples

ex <- example_landscape()
meta <- data.frame(sample_id = seq_len(nrow(ex$profiles)), x = ex$profiles$x,
                   y = ex$profiles$y)
elevation <- terra::rast(file.path(ex$raster_dir, "elevation.tif"))
knndm_folds(meta, k = 3, predpoints = prediction_sample(elevation, size = 500))
#> <fold_plan> knndm_folds | 3 fold(s) | 160 rows in the store
#>   params: k=3 | test_frac=0 | n_test=0 | seed=42 | W=138.6 | W_test_split=NA | projection=+proj=moll +lon_0=0 +datum=WGS84 +units=m
#> # A tibble: 3 × 4
#>    fold n_train n_validation n_test
#>   <int>   <int>        <int>  <int>
#> 1     1      95           65      0
#> 2     2     105           55      0
#> 3     3     120           40      0