misc/sandbox/IPA-algorithm-test.R

In ncss-tech/aqp: Algorithms for Quantitative Pedology

## testing IPA concept
# https://iopscience.iop.org/article/10.1088/1748-9326/abbb00/pdf
# https://www.publish.csiro.au/sr/pdf/SR9760291

## is that latest version correct?


library(aqp)
library(soilDB)

x <- fetchKSSL('musick')

x <- trunc(x, 0, 150)

x$IPA <- profileApply(x, simplify = TRUE, function(i) {
  
  var(i$sand, na.rm = TRUE) / mean(i$sand, na.rm = TRUE)
  
})

plotSPC(x, color = 'sand')

o <- order(x$IPA)
plotSPC(x, color = 'sand', plot.order = o)
text(1:length(x), 350, round(x$IPA, 2)[o])
axis(side = 1, at = 1:length(x), labels = format(x$IPA, digits = 3)[order(x$IPA)], cex.axis = 0.66, las = 1)