Selecting n cells more then minDist apart

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Hi Rainer,

how about aggregating to a lower resolution, where the cell center
- cell center distances correspond to your minDist? Then sample as
one would normally and then take the cell center coordinates from
your sample back to your original raster.

Wouldn't work in my case, as the underlying raster on which I want to
sample, has sometimes single isolated cells, and it is important to
have a chance of sampling these as well in a later step. And if under
the aggregated resolution two of these isolated cells are in one
celll, there is a problem.

A bit of geometry will tell you what the resolution needs to be
and please tell me you are not sampling a longlat projection!

No - its a UTM grid.

I looked again at my application, and I realized as I can also set the
minimum distance, and then distribute the points. So I decided to use
the r.random.cells function and specify the distance.

My application is a sensitivity analysis, and it does not matter if I
change the distance which results in different number of cells
selected, or change the number of cells and then distribute them.

Thanks a lot for your help,

Rainer

Either the r.region GRASS function or the aggregate 'raster'
function should do.

there's my cents/sense...

HTH,

Brian

- -- 
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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