Minimum pairwise distance within a selection

Returns the minimum pairwise distance among selected points \(T_k\). A set of points that is more dispersed will exhibit a higher value.

Usage

MinDist(d = NULL, idx, points = NULL)

Arguments

d: Pairwise distance matrix or dist object. Ignored when points is supplied.
idx: Integer vector of selected row/col indices.
points: Optional N x dim numeric coordinate matrix. When supplied, the score is computed from stats::dist() on the selected sub-coordinates only (k x k).

Value

MinDist() returns a numeric specifying the minimum distance between two selected points (or NA_real_, if length(idx) < 2).

Details

The solvers in this package (FarFirst(), DropAdd(), Grasp()) already attach the achieved \(T_k\) as a score attribute. MinDist() allows arbitrary selections to be scored, or an existing selection to be scored against a different distance matrix.

Examples

set.seed(1)
pts <- matrix(rnorm(60), ncol = 2)
d <- dist(pts)
MinDist(d, FarFirst(5L, d))
#> [1] 1.765223