I uploaded gstat 0.9-12 to CRAN, which has a few important changes:
1. Cokriging cross validation
Cokriging cross validation is now possible with the function gstat.cv:
you simply pass a multivariable gstat object, and cross validation is done
for the first variable in the object. Optionally, secondary variable records
at locations coinciding with the validation locations are removed.
2. Class name changes
Both gstat and geoR used the name "variogram" for -- highly incompatible -- objects that contain information about a variogram. This led to errors when calling plot() with a variogram object calculated from one, but plotted by the other package. I changed the class name into "gstatVariogram". The full list of class name changes:
variogram -> gstatVariogram point.pairs -> pointPairs variogram.map -> variogramMap variogram.cloud -> variogramCloud
You can still run scripts you have with the new packages, but e.g. plot(v) when v is an old object of class "variogram" will not work with the new package. As these are S3 classes, a simple solution would be to reassign the class:
class(v) = c("gstatVariogram", "data.frame")3. Compatibility with package sp and variogram maps On http://sourceforge.net/projects/r-spatial/ beta releases for the upcoming package sp are available; sp provides classes and methods for spatial data. Instead of:
> library(gstat) > data(meuse) > variogram(zinc~1, ~x+y, meuse)
you could, with package sp loaded, do:
> coordinates(meuse) = ~x+y # promotes meuse to SpatialDataFrame > variogram(zinc~1, meuse) # no coordinates required.
In addition, sp provides classes for gridded data and polygon data. With sp loaded, gstat can calculate variogram maps.
Any comments are welcome, -- Edzer
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