[GRASS-stats] Nearest neighbour distance distribution but between polygons

[Roger Bivand]

On Mon, 7 May 2012, Rainer M Krug wrote:

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> Hi
>
> I have the following (presumibly simple?) question:
>
> I have a certain number of patches (islands) in a landscape of which I 
> need to know the nearest neighbour distance. As the problem is related 
> to dispersal, I would need to know the actual shortest distance between 
> the actual polygons and not only the centroids. Is there an easy way to 
> obtain these in R or in GRASS? I am only aware of nearest neighbour 
> distance between points.

In R, if the coordinates are projected, use gDistance(..., byid=TRUE) in 
the rgeos package to get a matrix in the metric of the projection. If not 
projected, project if possible.

I don't think that the geosphere package provides for the unprojected 
case.

Roger

>
> Thanks,
>
> Rainer
>
>
> - --
> Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology, UCT), Dipl. Phys.
> (Germany)
>
> Centre of Excellence for Invasion Biology
> Stellenbosch University
> South Africa
>
> Tel :       +33 - (0)9 53 10 27 44
> Cell:       +33 - (0)6 85 62 59 98
> Fax :       +33 - (0)9 58 10 27 44
>
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>
> email:      Rainer at krugs.de
>
> Skype:      RMkrug
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-- 
Roger Bivand
Department of Economics, NHH Norwegian School of Economics,
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