Re: Adjacency matrices

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Re: Adjacency matrices

Nicholas Lewin-Koh
Hi,
>From the sound of this it is time
to grit my teeth and get the quadtree code working for maptools.
That should translate for a polygon list from Spdep and allow
calculation of adjacency matrices in R for moderate to large maps.

Oh if I could put time in a bottle ......


Nicholas



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Re: Adjacency matrices

Roger Bivand
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On Thu, 23 Oct 2003, Nicholas Lewin-Koh wrote:

> Hi,
> >From the sound of this it is time
> to grit my teeth and get the quadtree code working for maptools.
> That should translate for a polygon list from Spdep and allow
> calculation of adjacency matrices in R for moderate to large maps.

Actually poly2nb() isn't too slow for small data sets, such as those most
of the GeoBUGS users seem to need, and for Windows users GeoDa does pretty
well. I think Barry Rowlingson has (?) some quadtree code, but you are
right, there is some in or near shapelib too (shptree?). This would give
better spatial searching too (which poly is locator() in?), wouldn't it?
Is this functionality that would be appreciated?

>
> Oh if I could put time in a bottle ......
>

Let me know if you find a way - CET people get one hour extra early Sunday
morning!

Roger

>
> Nicholas
>
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> R-sig-Geo at stat.math.ethz.ch
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>

--
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand at nhh.no



Roger Bivand
Department of Economics
Norwegian School of Economics
Helleveien 30
N-5045 Bergen, Norway
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