Re: Fast calculation of block-block covariance

Thank you, for the fast replay. I will  read up on
this package of David Clifford and will inform you
if it provide a solution to my problem.


Best regards

Christoph



Am 16.05.2006 um 10:59 schrieb Edzer J. Pebesma:

> Christoph,
>
> package spatialCovariance (on CRAN) seems to do this, by reading
> it's description. Please share with us whether it did what you wanted
> or not; I acknowledge that this is a problem that other packages could
> benefit from a fast solution to this problem.
>
> Bests,
> --
> Edzer
>
> Christoph Hofer wrote:
>> Dear all
>>
>> I'm a Ph.D. student in Environmental Sciences at the ETH Zurich  
>> and   new to this list, but I have searched for an answer to my  
>> problem in  the list archives and couldn't find anything.
>>
>> I have the following problem:
>> I want to calculate the block-block covariance C(B1,B2) among two   
>> blocks  of arbitrary  shaped polygons (non-rectangular). In the  
>> gstat  package the block-block covariance is calculated by  
>> discretizing the  blocks by points (via the command  "nblockdiscr"  
>> one can choose the  number of points in the polygon).
>> I wrote R code with the function integrate, but to calculate the   
>> block-block covariance a quad integral of the covariance function  
>> has  to be calculated and  therefore even for polygons with a few  
>> vertices  my code is  very slow.
>>
>> Is there a fast solution (algorithm, package or function in R,  
>> aside  from the gstat solution) to calculate the block-block  
>> covariance of  arbitrary shaped polygons?
>>
>> Best regards
>>
>> Christoph Hofer
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo@xxxxxxxxxxxxxxxxx
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>
>