Compute weights from distance matrix
Function for computing a matrix of gaussian or fixed weights from distance matrix
spweights(distmat, h = NULL, kernel = "gaussian")
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'. |
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).
An object of class spatialweights
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")
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