Re: [R-sig-Geo] raster: stackApply problems..

2019-11-22 Thread Jon.SKOIEN
Leonidas, I see that you are not happy with the output, but it is not so clear what you actually expect to see. If you use stackApply directly, the indices are used in the names. Layer 1 and 8 belong to the group with index 4. It is the first group in the list of indexes, so the first layer o

Re: [R-sig-Geo] Warning in fit.variogram: value out of range in 'bessel k' | automap and gstat packages

2019-09-16 Thread Jon.SKOIEN
Hi Frederico, gstat does not have different behaviour, because autofitVariogram is using fit.variogram, after some preprocessing. You get the convergency problems with fit.variogram because you don't supply start values for the variogram, which is done in the preprocessing of autofitVariogram.

Re: [R-sig-Geo] Warning in fit.variogram: value out of range in 'bessel k' | automap and gstat packages

2019-09-11 Thread Jon.SKOIEN
Frederico, I don't think you need to worry about this warning in this case. autofitVariogram tests a lot of variogram models (and different kappa-values) in the search for the best one, and then fit.variogram tries to optimize the parameters based on these. It seems the warnings were generate

Re: [R-sig-Geo] Problems with gstat gaussian variogram and cross validation when fix nugget at 0

2018-10-16 Thread Jon.SKOIEN
Stefano, Fixing the nugget at zero for the Gaussian varigoram can often cause numerical problems in kriging. If you have two observations that are close in space, their modelled semivariance will be so small that you get numerical issues with the covariance matrix. In some cases it will be sing