[R-sig-Geo] directional correlograms

[Roger Bivand]

On Tue, 26 Jun 2007, Koppel, Johan van de wrote:

> Dear all,
>
>
>
> I have a question regarding the spdep package. I want to produce
> directional (anisotropic) correlograms. Is there any way to generate
> these with spdep?
>
>
>
> I am analyzing aerial photographs of patterned ecosystems, in which the
> patterns are often directional.
>

It is not impossible, but is not easy either. Having generated distance 
based neighbour lists, you will need to use the glist= argument to 
nb2listw() to zero out neighbours in the excluded direction subset, and 
getting the direction is not provided for in functions in spdep. So the 
main task is to generate a 0/1 glist to express direction. Are there 
direction functions that could be called in an lapply() on the neighbours 
list and a coordinate matrix?

Roger

>
>
> Thanks in advance,
>
>
>
> Johan
>
>
>
> ---------
> Johan van de Koppel
> Spatial Ecology Department
> Netherlands institute of Ecology
> Centre for Estuarine and Marine Ecology
> P.O. Box 140, 4400AC Yerseke, The Netherlands
> Phone: 31 (0)113 577455
>
> Mobile: 06-15402485
> Fax: 31 (0) 113 573616
> Email: J.vandeKoppel at nioo.knaw.nl
> Homepage: http://www.nioo.knaw.nl/homepages/koppel
> <http://www.nioo.knaw.nl/homepages/koppel>
>
>
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>
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no