[GRASS-stats] gstat error

[Jarek Jasiewicz]

Thanks you!
 it means problem is with spgras6, and default option plugin=NULL

as I know (but I can be absolutely wrong)  if plugin option is not set, 
it ussualy is set to TRUE if grass region and file extend are the same. 
But by default, using OGR directly on grass data import file as it is in 
GRASS ie. as 3d vector

it simply means that from grass, point file for kriging interpolation 
shoud be imported with plugin=FALSE
in that way all works fine.

It explains why it work earier

thanks for your help and suggestion

Jarek

Edzer Pebesma pisze:
> Jarek has sent me the data off-line, and it turns out that the data are
> three-dimensional, but lack variability in the third dimension:
>
>   
>> summary(p)
>>     
> Object of class SpatialPointsDataFrame
> Coordinates:
>               min     max
> coords.x1 3560158 3575935
> coords.x2 5636873 5653748
> coords.x3       0       0
> Is projected: TRUE
> proj4string :
> [+proj=stere +lat_0=51.67083333333333 +lon_0=16.67222222222222
> +k=0.999800 +x_0=3703000 +y_0=5627000 +no_defs +a=6378245 +rf=298.3
> +towgs84=33.4,-146.6,-76.3,-0.359,-0.053,0.844,-0.84 +to_meter=1]
> Number of points: 200
> Data attributes:
> ...
>
> Using the "degree=1" way of trend analysis, a first order linear trend
> is computed in the coordinates, meaning in z as well, and this is the
> cause of failure. Ignoring z, one can e.g. do
>
> p$x=coordinates(p)[,1]
> p$y=coordinates(p)[,2]
> r$x=coordinates(r)[,1]
> r$y=coordinates(r)[,2]
> pg=gstat(id="p_1", formula=rzedna~x+y,data=p)
> p_1=predict(pg,r)
> spplot(p_1)
>
> of course, no standardization of coordinates takes place here, so this
> approach will fail for high order trends.
> --
> Edzer
>
> Jarek Jasiewicz wrote:
>   
>> Edzer Pebesma pisze:
>>     
>>> Jarek Jasiewicz wrote:
>>>  
>>>       
>>>> Hi
>>>> during trend calculation I recive following error:
>>>>
>>>> R
>>>> library(spgrass6)
>>>> library(gstat)
>>>>
>>>> raster=readRAST6("rzedna")
>>>> p=readVECT6("punkty")
>>>> p at proj4string=raster at proj4string
>>>>
>>>> pg_1=gstat(id="p_1", formula=rzedna~1,data=p, degree=1)
>>>> p_1=predict(pg_1,raster)
>>>> [ordinary or weighted least squares prediction]
>>>>
>>>> "solve.c", line 87: singular matrix in function Usolve()
>>>> Error in predict.gstat(pg_1, raster) : Usolve
>>>>     
>>>>         
>>> There are several situations why this can happen that are hard to
>>> distinguish from the point where the error happens. The most likely in
>>> your case (first order trend surface estimation) is that your data are,
>>> geographically, on a line, i.e. one-dimensionally. Or similary, that you
>>> have less than 3 observations. Is that the case?
>>> -- 
>>> Edzer
>>>   
>>>       
>> Thanks for answer,  but none of that case. Tt is regular data file
>> with 200 random observations generated with v.random in GRASS and
>> stored as SpatialPointDataFrame.
>> before I  posted to the list  I had tried to reproduce it on my
>> archive data with archive scripts (which worked  in older R
>> compilation) and it ALWAYS fail (on every data I tested).
>>
>> In general, the possible problem on my side coud be that I
>> (experientally) installed R from CRAN ubuntu repository instead to
>> compile from source. The ubuntu CRAN-R packages do not include lapack.
>> This is the only difference I noticed.
>>
>> If you need I can send you sample R file (is small, no more than 2MB)
>>
>> Jarek
>>
>>     
>>>> my system information:
>>>>
>>>> Ubuntu 8.04
>>>> R 2.8.1
>>>> gstat 0.9.59
>>>> the error have appeared first time on gstat 0.9.49
>>>>
>>>> Errors apears on all my data, even these, where trend was calculated
>>>> some times ago. Commads coming from old data
>>>>
>>>> The error is also reproducible on spearfish dataset with elevation.dem
>>>> and random points generated by v.random
>>>>
>>>> Jarek
>>>> _______________________________________________
>>>> grass-stats mailing list
>>>> grass-stats at lists.osgeo.org
>>>> http://lists.osgeo.org/mailman/listinfo/grass-stats
>>>>     
>>>>         
>>>   
>>>       
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>>     
>
>