Calculate inverse distance weights

From a neighbor list and sf geometry column, calculate inverse distance weight.

Usage

st_inverse_distance(nb, geometry, scale = 100, alpha = 1)

Arguments

nb

a neighbors list object e.g. created by st_knn() or st_contiguity()

geometry

sf geometry

scale

default 100.a value to scale distances by before exponentiating by alpha

alpha

default 1. Set to 2 for gravity weights.

Value

a list where each element is a numeric vector

Details

The inverse distance formula is \(w_{ij} = 1 / d_{ij}^\alpha\)

See also

Other weights: st_kernel_weights(), st_nb_dists(), st_weights()

Examples

geo <- sf::st_geometry(guerry)
nb <- st_contiguity(geo)
wts <- st_inverse_distance(nb, geo)
#> ! Polygon provided. Using point on surface.
head(wts, 3)
#> [[1]]
#> [1] 0.001110733 0.001144174 0.001798959 0.001166951
#> 
#> [[2]]
#> [1] 0.0011734145 0.0013168726 0.0007953086 0.0011521100 0.0009777799
#> [6] 0.0009476921
#> 
#> [[3]]
#> [1] 0.0011701250 0.0010803469 0.0010350414 0.0011362283 0.0015060218
#> [6] 0.0008947445
#> 
wts <- st_inverse_distance(nb, geo, scale = 10000)
#> ! Polygon provided. Using point on surface.
head(wts, 3)
#> [[1]]
#> [1] 0.1110733 0.1144174 0.1798959 0.1166951
#> 
#> [[2]]
#> [1] 0.11734145 0.13168726 0.07953086 0.11521100 0.09777799 0.09476921
#> 
#> [[3]]
#> [1] 0.11701250 0.10803469 0.10350414 0.11362283 0.15060218 0.08947445
#>