[GRASS-dev] v.perturb

Moritz Lennert mlennert at club.worldonline.be
Thu Aug 28 04:49:41 PDT 2014

On 27/08/14 00:12, Alessandro Samuel Rosa wrote:
> Dear GRASS GIS developers,
> I am planning to use v.perturb to run a spatial simulated annealing
> exercise. Two drawbacks with v.perturb exist. First, "output vector
> points are not guaranteed to be contained within the current geographic
> region". Second, all vector points are perturbed together.
> Is it very difficult to solve this issues?

What exactly are your objectives ?

You can use v.extract with the random= option or v.kcv+v.extract to 
create a sample of points you can then perturb instead of perturbing all 

To make sure your points still fall into the region, you can use 
v.in.region to create a polygon representing the region, then v.select 
within your sample those that fall into the polygon.


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