rcarbon (version 1.4.4)

spweights: Compute weights from distance matrix

Description

Function for computing a matrix of gaussian or fixed weights from distance matrix

Usage

spweights(distmat, h = NULL, kernel = "gaussian")

Value

An object of class spatialweights

Arguments

distmat

a symmetric matrix of inter-site distances (in km).

h

parameter of the Gaussian distance decay function.

kernel

indicates the type of weighting function, either 'fixed' or 'gaussian'. Default is 'gaussian'.

Details

This function generates a weight matrix (required for the SPpermTest) function. When kernel=="fixed", the weight \(w_{ij}\) between site \(i\) and \(j\) is equal to 1 when their interdistance \(d_{ij}\) is below h, and equal to 0 when \(d_{ij}>h\).When kernel=="gaussian", the weight is calculated with formula exp(-d_ij^2/h^2).

Examples

lon <- c(11.3426,0.1278,0.1218)
lat <- c(44.4949,51.5074,52.2053)
library(sp)
d <- spDists(x=cbind(lon,lat),y=cbind(lon,lat))
spweights(d,h=100)
spweights(d,h=100,kernel="fixed")