Pairwise geographic or elevational distances

Great-circle (haversine) or elevational distances between sites, as a long tibble ready to join with tidydiversity::beta_pair() or to build a geo_decay() distance-decay table. Elevational distance is the absolute difference in metres.

Usage

geo_distance(
  data,
  lon = lon,
  lat = lat,
  elevation = NULL,
  site = site,
  method = c("haversine", "elevation", "euclidean", "environmental"),
  vars = NULL,
  scale = TRUE,
  metric = c("euclidean", "gower"),
  .by = NULL
)

Arguments

data

A data frame of unique sites (or records constant within site) with coordinates and optional elevation.

lon, lat, elevation, site

<data-masking> Column selections.

method

"haversine" (metres), "elevation" (metres), "euclidean" on lon/lat in degrees, or "environmental" for Euclidean or Gower distance on numeric covariate columns (for example bioclim layers from geo_extract() / geo_bioclim()).

vars

Character vector of covariate columns for method = "environmental". When NULL, every numeric column except coordinates, elevation and the site id is used.

scale

Standardise environmental columns to mean 0 and sd 1 before Euclidean distance? Ignored for Gower.

metric

"euclidean" or "gower" for environmental distances.

.by

Optional grouping columns.

Value

A tibble with site_1, site_2, distance and grouping columns.

Examples

sites <- tibble::tibble(
  site = c("a", "b", "c"),
  lon = c(147.0, 147.1, 147.2),
  lat = c(-9.4, -9.5, -9.6),
  elevation = c(200, 700, 1200)
)
geo_distance(sites, lon, lat, method = "haversine")
#> # A tibble: 3 × 3
#>   site_1 site_2 distance
#>   <chr>  <chr>     <dbl>
#> 1 a      b        15619.
#> 2 a      c        31236.
#> 3 b      c        15617.
geo_distance(sites, elevation = elevation, method = "elevation")
#> # A tibble: 3 × 3
#>   site_1 site_2 distance
#>   <chr>  <chr>     <dbl>
#> 1 a      b           500
#> 2 a      c          1000
#> 3 b      c           500