bestkappa {geosimilarity}

Function for the best kappa parameter

Description

Function for determining the best kappa parameter for the optimal similarity

Usage

bestkappa(formula, data = data, kappa = seq(0.05,1,0.05), nrepeat = 10)

Arguments

formula

A formula of GOS model

data

A data.frame of observation data

kappa

A numeric vector of the optional percentages of observation locations with high similarity to a prediction location. kappa = 1 - tau, where tau is the probability parameter in quantile operator. kappa = 0.25 means that 25 location are used for modelling.

nrepeat

A numeric value of the number of cross-validation training times. The default value is 10.

Value

A list of the result of the best kappa and the computation process.

Examples

data("zn")
# log-transformation
hist(zn$Zn)
zn$Zn <- log(zn$Zn)
hist(zn$Zn)
# remove outliers
require(SecDim)
k <- rmvoutlier(zn$Zn, coef = 2.5)
dt <- zn[-k,]
# determine the best kappa
system.time({
b1 <- bestkappa(Zn ~ Slope + Water + NDVI  + SOC + pH + Road + Mine,
                data = dt,
                kappa = c(0.01, 0.1, 1),
                nrepeat = 1)
})
b1$bestkappa
b1$plot