[R] non-stationary covariance

[ripley@stats.ox.ac.uk]

There are at least three R packages to do this, spatial, geoR and
sgeostat. Look at library(help=) for each.

On Wed, 3 Apr 2002, Lecca Paola wrote:

> Hi !
>
> Sorry for my ignorance. I have two questions:
>
> 1) which is in R the function to make a covariogram of spatial data ?
>
> 2) does anyone know if there exist the possibility in R of performing
> kriging with an arbitrary covariance function ?

Certainly.  It's just linear algebra which R does fairly well (and I've
written code to do so in S long ago, when it was too slow on a 12Mb 20MHz
machine).

> If I have well understood the Krig procedure offers only three
> possibilities (expcov, gauscov and sphercov) that are the common models
> for stationary and isotropic processes.

surf.gls allows arbitrary stationary and isotropic processes, for example.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._