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

[Rainer M Krug]

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On 07/05/12 14:35, G. Allegri wrote:
> In Grass maybe you could use the boundaries instead of the areas. The distances would be
> between the boundaries' linestrings instead of centroids.

Sounds definitely like an option to keep in mind - but what Roger suggested is easier to implement
right now.

Thanks,

Rainer

> 
> giovanni
> 
> 2012/5/7 Roger Bivand <Roger.Bivand at nhh.no <mailto:Roger.Bivand at nhh.no>>
> 
> On Mon, 7 May 2012, Rainer M Krug wrote:
> 
> 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
> 
> 
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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 <tel:%2B47%2055%2095%2093%2055>; fax +47 55 95 95
> 43 <tel:%2B47%2055%2095%2095%2043> e-mail: Roger.Bivand at nhh.no <mailto:Roger.Bivand at nhh.no>
> 
> 
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> 

- -- 
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
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Skype:      RMkrug
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