spweights: Compute weights from distance matrix

Description Usage Arguments Details Value Examples

View source: R/utilities.R

Description

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

Usage

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

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).

Value

An object of class spatialweights

Examples

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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")

rcarbon documentation built on Oct. 1, 2018, 5:03 p.m.