[R-sig-Geo] kriging: export to grid

[Edzer Pebesma]

Hi Paulo,

you suggest to add conversion functions to geoR later on, but I (as the 
average lazy user) would ask the following: if in the following geoR call

kc.s <- krige.conv(s100, loc=gr.s, krige=krige.control(obj=ml.s))


gr.s is of class SpatialPixels[DataFrame] or SpatialGrid[DataFrame], 
could, as output, the object kc.s be of that same class? You could argue 
this is incompatible, but a call like that was never supposed to work so 
you could call it progress as well. And it saves me the conversion. Of 
course, gr.s and kc.s could be of class SpatialPoints[DataFrame] as well.

Bests regards,
--
Edzer

Paulo Justiniano Ribeiro Jr wrote:
> I've just added to the geoR tutorial page an script with examples
> on converting geoR's krige.conv() outputs to
> SpatialGridDataFrame and SpatialPixelDataFrame formats defined by the sp
> package
>
> The relevant link is:
> http://leg.ufpr.br/geoR/tutorials/kc2sp.R
>
> These should be encapsulated on function in a (hopefully) near future
> to facilitate conversion of outputs from both, krige.conv() and
> krige.bayes()
>
>
> As usual, comments/suggestions/improvements etc are very welcome!
>
> Best
> P.J.
>
>
> Paulo Justiniano Ribeiro Jr
> LEG (Laboratorio de Estatistica e Geoinformacao)
> Universidade Federal do Parana
> Caixa Postal 19.081
> CEP 81.531-990
> Curitiba, PR  -  Brasil
> Tel: (+55) 41 3361 3573
> Fax: (+55) 41 3361 3141
> e-mail: paulojus AT  ufpr  br
> http://www.leg.ufpr.br/~paulojus
>
>
>
> On Sun, 14 Dec 2008, Roger Bivand wrote:
>
>   
>> On Sun, 14 Dec 2008, Nicolas Meurisse wrote:
>>
>>     
>>> Hello,
>>>
>>> After kriging with the use of the  krige.conv function, I would like to
>>> export my result under the grid format. In order to view it into a GIS.
>>>
>>> It was suggested to me to use the writeGDAL function into the rgdal package.
>>> However It looks like I have a problem of supported formats
>>> (dataset object of SpatialGridDataFrame-class or SpatialPixelsDataFrame-class
>>> ) that is not the same as the one resulting from my krige.conv function
>>> (kriging -class apparently)
>>>
>>> I tried several function to achieve this conversion (getRasterData,
>>> SpatialGridDataFrame, SpatialPixelsDataFrame, create2GDAL, points2grid...).
>>> But without any success.
>>>
>>> #my actual kriging script:
>>> pred.grid = expand.grid(seq(170000, 130000, l = 50), seq(190000, 160000, l =
>>> 50))
>>>       
>> library(sp)
>> pred.grid$var3 <- 1
>> coordinates(pred.grid) <- c("Var1", "Var2")
>> gridded(pred.grid) <- TRUE
>>
>> # Create a SpatialPixelsDataFrame or SpatialGridDataFrame object first
>> # - forced here by including a non-coordnate column to the data frame
>>
>>     
>>> myPred = krige.conv(myGData, loc = pred.grid, krige = krige.control(obj.m =
>>> myOLSMod))
>>>       
>> myPred = krige.conv(myGData, loc = coordinates(pred.grid),
>>   krige = krige.control(obj.m = myOLSMod))
>>
>> # Krige with the coordinates of the object
>>
>> pred.grid$predict <- myPred$predict
>>
>> # add the predictions (and standard errors if you like) to the
>> # object, they are in the correct order;
>> # then write out, choosing the output column as desired
>>
>> tf <- tempfile()
>> writeGDAL(pred.grid["predict"], tf, drivername="GTiff") # not type="Byte"!
>> GDALinfo(tf)
>>
>> # I suppose you are using the temporary file here to test your approach
>> # as you ought to put the output file in a permanent place if you will
>> # need it later
>>
>> Hope this helps,
>>
>> Roger
>>
>>     
>>> image(myPred, loc = pred.grid, col = gray(seq(1, 0.1, l = 30)))
>>>
>>> #my conversion attempts
>>> tf <- tempfile()
>>> writeGDAL(myPred, tf, drivername="GTiff", type="Byte", options=NULL)
>>> [Erreur dans function (classes, fdef, mtable) : unable to find an inherited
>>> method for function "gridded", for signature "kriging"]
>>>
>>> Thanks a lot,
>>>
>>> Nicolas
>>>
>>> _______________________________________________
>>> R-sig-Geo mailing list
>>> R-sig-Geo at stat.math.ethz.ch
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>
>>>       
>> --
>> 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
>>
>> _______________________________________________
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>>
>>     
>
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-- 
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster
Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
8333081, Fax: +49 251 8339763 http://ifgi.uni-muenster.de/
http://www.springer.com/978-0-387-78170-9 e.pebesma at wwu.de