[R-sig-Geo] about ST kriging
Pınar Aslantas Bostan
aslantas at metu.edu.tr
Thu Sep 22 14:39:08 CEST 2011
Edzer, I have 256 meteorological station and 39 year value.
 256 39 1
Before I tried only spatial kriging and I did not get memory.size error. Just a moment ago, I used another computer (64-bit Windows and 6 GB RAM), again I got the same error.
From: Edzer Pebesma [mailto:edzer.pebesma at uni-muenster.de]
Sent: Thursday, September 22, 2011 2:47 PM
To: Pınar Aslantas Bostan
Cc: r-sig-geo at r-project.org
Subject: Re: [R-sig-Geo] about ST kriging
Pinar, what are the dimensions (space and time) of your data, i.e. what
does dim(w) return?
Have you tried kriging with a (spatial and/or temporal) subset?
On 09/22/2011 01:38 PM, Pınar Aslantas Bostan wrote:
> Hi Edzer,
> Thank you very much for your mail. I found two records have identical location, but it is not my fault because I checked the original source data and it is erroneous.
> Now I have another problem; R gives another error message:
> Error: cannot allocate vector of size 95.4 Mb
> My computer includes 32-bit Windows and 3,5 GB RAM. I am not sure if I install 64-bit Windows, then the problem is solved? Or maybe I should minimize the data. Do you have any idea about it?
> Best wishes,
> -----Original Message-----
> From: r-sig-geo-bounces at r-project.org [mailto:r-sig-geo-bounces at r-project.org] On Behalf Of Edzer Pebesma
> Sent: Wednesday, September 21, 2011 3:46 PM
> To: r-sig-geo at r-project.org
> Subject: Re: [R-sig-Geo] about ST kriging
> Hi Pinar,
> it is not clear which variogram model you pass, or how your data are
> laid out in space and time.
> Possible causes for a non-positive definite covariance matrix include:
> - a variogram model with (nearly) perfect correlation
> - duplicate observations (observations having identical location AND time)
> - an invalid variogram model
> A small, reproducible example (data + script) would help identify the
> Best regards,
> On 09/20/2011 11:15 AM, Pınar Aslantas Bostan wrote:
>> Dear all,
>> I am working about space-time kriging. Before I asked again about ST kriging
>> but now the problem is
>> different and I could not overcome it!
>> During kriging operation I got this error:
>>> pred = krigeST(prec~1, w, STS(grid,time,index), v)
>> Error in chol.default(A$Sm, LINPACK = TRUE) :
>> non-positive definite matrix in 'chol'
>> I explained the data set below:
>> # prec is annual precipitation measured from 257 meteorological stations
>> # w is STSDF object
>> Object of class STSDF
>> Object of class SpatialPoints
>> min max
>> Xnew 140556 1730472
>> Ynew 4309064 4971309
>> Is projected: NA
>> proj4string : [NA]
>> Number of points: 257
>> Index object at time
>> Min. :1970-01-01 12:00:00 Min. : 1.0
>> 1st Qu.:1979-07-03 00:00:00 1st Qu.:10.5
>> Median :1989-01-01 12:00:00 Median :20.0
>> Mean :1989-01-01 02:46:09 Mean :20.0
>> 3rd Qu.:1998-07-03 00:00:00 3rd Qu.:29.5
>> Max. :2008-01-01 12:00:00 Max. :39.0
>> [[Data attributes:]]
>> Min. 1st Qu. Median Mean 3rd Qu. Max.
>> 114.5 413.7 533.6 633.0 735.6 3332.0
>> # I used grid to obtain predictions over it. It has 25 km spatial resolution
>> # time is temporal entity of study. It contains 39 annual observation.
>> # index is required for STSDF, and I used this code to create index.
>>> index <- cbind(as.integer(as.factor(data$Station)),
>> # v is space-time variogram
>> How can I solve the problem?
>> Thank you in advance!
>> Pinar Aslantas Bostan
>> Research Assistant
>> Department of Geodetic and
>> Geographic Information Technologies (GGIT) Middle East Technical University
>> 06531 Ankara/TURKEY
>> aslantas at metu.edu.tr
>> R-sig-Geo mailing list
>> R-sig-Geo at r-project.org
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