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 at 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 =
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"
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"
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 at uni-muenster.de>
Date: 14 November 2013 21:15
Subject: Re: Regression kriging
To: Jordan Chetcuti <chetcuti at 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
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.
the moment I can't seem to find a solution.
Any help would be greatly received.
Sincerely
Jordan Chetcuti