Calculate area/volume of kde output from ks package
Hi I'm trying to calculate the volume of a 3D kernel density estimator that has been calculated using the kde command from the ks package. So far I'm just working with the examples given before applying this to my own data so only have that example data to give (found under "plot" of the package manual): ## trivariate example library(MASS) x <- iris[,1:3] H.pi <- Hpi(x, pilot="samse") fhat <- kde(x, H=H.pi, compute.cont=TRUE) plot(fhat, drawpoints=TRUE) Under a previous post about calculating the 2D spatial area of the kde output (see full original message at the end) the following was suggested: " Michael Sumner-2 wrote
Here's one way: library(ks) data(unicef) H.scv <- Hscv(x=unicef) fhat <- kde(x=unicef, H=H.scv) image(fhat$eval.points[[1]], fhat$eval.points[[2]], fhat$estimate) library(sp) spkde <- image2Grid(list(x = fhat$eval.points[[1]], y = fhat$eval.points[[2]], z = fhat$estimate)) contour(spkde, add = TRUE) " - How would this above method be applied to a 3D kde output? How would you calculate the kde output at specific contour levels? Such as the 95% or 50% contour levels. The original R-sig-geo post quoted a wiki page that seems to have subsequently removed the posting about image2Grid. Many thanks, Kathryn On Sat, Nov 28, 2009 at 7:53 AM, Tyler Dean Rudolph <prairie.picker@> wrote:
?Is there a way to convert a kde object (ks package) into a spatial object (e.g. SpatialPixels, SpatialPolygons) for export into a GIS? ?Alternatively, is there a way to generate the 2-D spatial area underneath the 3-D utilisation distribution of a kde object? ?I have explored the package descriptions and help forums and have not yet found a solution.... Tyler ? ? ? ?[[alternative HTML version deleted]]
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