Hi Ashton,

Thanks for taking the time to email me.

I alas don't have the variables for all locations in the "blank" dataset. I
am beginning to wonder if I entirely understand regression kriging (or in
fact if any of my class really understand this).

Having the variables at more locations than the "bd" dataset, makes this
seem similar to co-kriging.

That would make more sense, I had wondered how the regression was worked
out for each prediction location.

Thanks again.

Regards

Jordan





On 18 November 2013 03:40, Ashton Shortridge <ashton@msu.edu> wrote:

> Hi Jordan,
>
> I always use the 'data' parameter when kriging. Here's how I'd do it:
>
> class(bd)   # This should be a SpatialPointsDataFrame
> names(bd) #  all the variables in the model (Total, m5005CVOL, etc)
>
> class(blank) # This should be a SpatialPointsDataFrame
> names(blank) # all the variables in the model except for Total
>
> TotalRegKrige <- krige(Total~m5005CVOL+n50010CVOL+n50015CVOL+DTM, bd,
> blank,
> model=fit_r)
>
>
> Hope this helps.
>
> Ashton
>
>
>
> On Friday, November 15, 2013 10:10:30 AM Jordan Chetcuti wrote:
> > Hello, I was wondering if anyone has encountered this issue?
> >
> >
> > This line works:
> >                       TotalKrige <- krige(Total~1, locations=bd,
> > newdata=blank, model=fit_Total)
> >
> > This line does not:
> >                      TotalRegKrige <-
> > krige(Total~m5005CVOL+n50010CVOL+n50015CVOL+DTM, locations=bd,
> > newdata=blank, model=fit_r)
> >
> > Message:
> >                      Error in eval(expr, envir, enclos) : object
> > 'm5005CVOL' not found
> >
> > I have emailed the author of the library "gstat", he very helpfully
> > offered some advice and that I post here. I have also included my
> > intial email exchange with Prof. Pebesma.
> >
> > I have included a description of my two datsets below and the
> > libraries I have loaded.
> >
> > data = locations (therefore it isn't necessary to have "data"
> > specified (in the way it is in a linear model lm() )
> > newdata = the locations to krige
> >
> > I have also tried among other things:
> >
> > TotalRegKrige <-
> > krige(Total~bd$m5005CVOL+bd$n50010CVOL+bd$n50015CVOL+bd$DTM,
> > locations=bd, newdata=blank, model=fit_r)
> >
> > Giveing:
> >
> > Error in gstat.formula.predict(d$formula, newdata, na.action =
> na.action,  :
> > NROW(locs) != NROW(X): this should not occur
> > In addition: Warning messages:
> > 1: 'newdata' had 26026 rows but variables found have 83 rows
> > 2: 'newdata' had 26026 rows but variables found have 83 rows
> >
> > This would lead me to think there is an error in the ascii grid,
> > except that it worked perfectly in the ordinary kriging example.
> >
> > Any help anyone can give would be greatly appreciated.
> >
> > Regards
> >
> > Jordan Chetcuti
> >
> > p.s. see descriptions of data and libraries below, and conversation
> > with Prof. Pebesma.
> >
> >
> > Dataset "bd"
> >
> > > summary(bd)
> >
> > Object of class SpatialPointsDataFrame
> > Coordinates:
> >       min     max
> > X  228112  232468
> > Y 2190072 2195810
> > Is projected: NA
> > proj4string : [NA]
> > Number of points: 83
> > Data attributes:
> >    StationID       m1K10CrnR       m1K10TrHT       m1K10CVOL (only
> > first few, contains many).
> >
> > Dataset "blank"
> >
> > > summary(blank)
> >
> > Object of class SpatialGridDataFrame
> > Coordinates:
> >          min     max
> > [1,]  226693  233843
> > [2,] 2187940 2197040
> > Is projected: NA
> > proj4string : [NA]
> > Grid attributes:
> >   cellcentre.offset cellsize cells.dim
> > 1            226718       50       143
> > 2           2187965       50       182
> > Data attributes:
> >    Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
> >       1       1       1       1       1       1
> >
> >
> > Libraries
> > 1. geoR
> > 2. gstat
> > 3. sp
> > 4. lattice
> >
> > >---------- Forwarded message ----------
> > >From: Edzer Pebesma <edzer.pebesma@uni-muenster.de>
> > >Date: 14 November 2013 21:15
> > >Subject: Re: Regression kriging
> > >To: Jordan Chetcuti <chetcuti@hawaii.edu>
> > >
> > >
> > >You omitted the error, which is:
> > >
> > >Error in eval(expr, envir, enclos) : object 'm5005CVOL' not found
> > >
> > >it means that in "blank", the prediction locations, m5005CVOL is not
> > >found (as is true of all other predictors).
> > >
> > >Please consider posting to r-sig-geo in the future.
> > >
> > >with best regards,
> > >
> > >Edzer Pebesma
> > >
> > >On 11/15/2013 03:30 AM, Jordan Chetcuti wrote:
> > >> Dear Prof. Pebesma,
> > >>
> > >> My name is Jordan Chetcuti and I am a graduate student at the
> University
> > >> of
> > >> Hawaii at Manoa, in the Geography department.
> > >>
> > >> I am attempting to do regression kriging on some of my data, but I am
> > >> alas
> > >> having a bit of a problem with gstat.
> > >>
> > >> within my script this line works:
> > >>
> > >> TotalKrige <- krige(Total~1, locations=bd, newdata=blank,
> > >> model=fit_Total)
> > >>
> > >> this does not:
> > >>
> > >> TotalRegKrige <- krige(Total~m5005CVOL+n50010CVOL+n50015CVOL+DTM,
> > >> locations=bd, newdata=blank, model=fit_r)
> > >>
> > >> The problem seems to be in the "newdata" when regression kriging
> > >> (replacing
> > >> "blank" with "bd" does not cause the error, although it also does not
> > >> krige
> > >> between the points)
> > >>
> > >> I was wondering if you would mind having a very quick look at this for
> > >> me?
> > >> My hope is that it is something I have simply mistyped. I've spent
> > >> considerable time writing vba, vb.net and python scripts and numerous
> > >> weeks
> > >> working in R recently and I am usually pretty good at de-bugging.
> Alas at
> > >> the moment I can't seem to find a solution.
> > >>
> > >> Any help would be greatly received.
> > >>
> > >> Sincerely
> > >>
> > >> Jordan Chetcuti
> >
> > _______________________________________________
> > R-sig-Geo mailing list
> > R-sig-Geo@r-project.org
> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
> -----
> Ashton Shortridge
> Associate Professor                     ashton@msu.edu
> Dept of Geography                       http://www.msu.edu/~ashton
> 235 Geography Building          ph (517) 432-3561
> Michigan State University               fx (517) 432-1671
>
>

	[[alternative HTML version deleted]]

