[STATSGRASS] Re: [R-sig-Geo] error in krig interpolation

[Roger Bivand]

On Thu, 5 Apr 2007, Edzer J. Pebesma wrote:

> el1 is already a SpatialPointsDataFrame, so omit the locations argument.
> 
> You may try something as simple as
> 
> zz <- krige(log(z) ~ 1, el1, mask_SG, efitted) 

The real problem is that "ORDINARY KRIGING IN R WITH GRASS6 DATA" is on a 
wiki with no responsible owner or maintainer, and no automatic way of 
synchronising it with current code:

http://grass.gdf-hannover.de/wiki/GRASS_6_Tutorial#GRASS_and_R_kriging_interpolation

The original is not signed, with no attached data sets or location, so we
can't ask anyone to keep it working.  I've added:

(WARNING!! Most of the code quoted here is very out of date, and simply 
does not work for current R/sp/gstat/spgrass6. Untried suggestions 
have been edited in, but without a test location, there is no 
guarantee that they will work! Roger Bivand, 5 April 2007)

at the top of the section, and tried to indicate the worst inaccuracies.

Roger

> 
> --
> Edzer
> 
> temiz wrote:
> > when does this error occur ?
> >
> >  > zz <- krige(formula = log(el1$z) ~ 1, locations = ~x+y , data = el1 
> > ,newdata = mask_SG , model = efitted) Error in function (classes, fdef, 
> > mtable)  :
> >         unable to find an inherited method for function "coordinates<-", 
> > for signature "SpatialPointsDataFrame"
> >
> >
> > str(el1) gives:
> >
> > Formal class 'SpatialPointsDataFrame' [package "sp"] with 5 slots
> >   ..@ data       :'data.frame': 24051 obs. of  4 variables:
> >   .. ..$ cat: num [1:24051] 1 2 3 4 5 6 7 8 9 10 ...
> >   .. ..$ x  : num [1:24051] 449114 449204 449262 449263 449276 ...
> >   .. ..$ y  : num [1:24051] 4590406 4590375 4590117 4590304 4590214 ...
> >   .. ..$ z  : num [1:24051] 110 110 110 110 110 110 110 110 110 110 ...
> >   ..@ coords.nrs : num(0)
> >   ..@ coords     : num [1:24051, 1:2] 449114 449204 449262 449263 449276 ...
> >   .. ..- attr(*, "dimnames")=List of 2
> >   .. .. ..$ : NULL
> >   .. .. ..$ : chr [1:2] "coords.x1" "coords.x2"
> >   ..@ bbox       : num [1:2, 1:2]  449083 4584531  456552 4591890
> >   .. ..- attr(*, "dimnames")=List of 2
> >   .. .. ..$ : chr [1:2] "coords.x1" "coords.x2"
> >   .. .. ..$ : chr [1:2] "min" "max"
> >   ..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slots
> >   .. .. ..@ projargs: chr " +proj=utm +zone=36 +ellps=intl +units=m 
> > +no_defs"
> >
> >
> >
> > regards
> >
> >
> 
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> 

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no