distances: Compute Distance Matrix

In spacc: Fast Spatial Species Accumulation Curves

Compute Distance Matrix

Description

Pre-compute pairwise distances between sites for reuse across multiple spacc() calls. Supports sf objects with accurate geodesic distances for global-scale studies.

Usage

distances(x, method = NULL, fun = NULL, which = NULL)

Arguments

x	Site locations. Can be: A data.frame with columns x and y An sf object with POINT geometries An sfc_POINT object
method	Character. Distance method: "euclidean": Euclidean distance (for projected coordinates) "haversine": Great-circle distance (for lat/lon, fast approximation "geodesic": Accurate ellipsoidal distance via sf/S2 (for global scale) Default is auto-detected from CRS when using sf objects.
fun	Optional custom distance function. Must take two coordinate vectors (x, y) and return a distance matrix. Overrides method.
which	For sf objects, column name containing the geometry. Default uses active geometry.

Details

For continental and global-scale studies, use sf objects with geographic CRS (e.g., EPSG:4326). The function will automatically use accurate geodesic distances via the S2 spherical geometry library.

For smaller study areas with projected coordinates (UTM, etc.), Euclidean distance is appropriate and faster.

Value

An object of class spacc_dist containing the distance matrix with coordinates stored as an attribute.

Examples

coords <- data.frame(x = runif(50), y = runif(50))
d <- distances(coords)

# Reuse for multiple analyses
species <- matrix(rbinom(50 * 30, 1, 0.3), nrow = 50)
sac <- spacc(species, d)

spacc documentation built on June 20, 2026, 5:07 p.m.