Build or validate anchor coordinates in MNI space

Usage

dkge_make_anchors(
  xyz = NULL,
  anchors = NULL,
  n_anchor = 20000L,
  method = c("kmeans", "sample"),
  seed = NULL
)

xyz: Optional \(N \times 3\) matrix of grey-matter coordinates (in mm). Used when anchors need to be derived from voxel locations.
anchors: Optional precomputed \(Q \times 3\) anchor matrix. When supplied it is validated and returned unchanged.
n_anchor: Target number of anchors when deriving them from `xyz`.
method: Selection strategy when deriving anchors. `"kmeans"` (default) uses k-means centroids, `"sample"` performs a uniform subsample.
seed: Optional random seed for reproducibility.

A numeric \(Q \times 3\) matrix of anchor coordinates.

xyz <- matrix(rnorm(200 * 3), 200, 3)
anchors <- dkge_make_anchors(xyz = xyz, n_anchor = 10, method = "sample", seed = 1)
dim(anchors)
#> [1] 10  3