[GRASS-dev] Creating / reading in random sample of raster values in Python script

[Laurent C.]

Hello,

If you need a fixed number of points, you might do a while loop that
randomly generate coordinates then add the point only if the array is not
null at those coordinates.

Laurent

On 25 Mar 2017 13:55, "Paulo van Breugel" <p.vanbreugel at gmail.com> wrote:

> On 25 March 2017 20:21:18 Luca Delucchi <lucadeluge at gmail.com> wrote:
>
> > Il 25/mar/2017 20:07, "Paulo van Breugel" <p.vanbreugel at gmail.com> ha
> > scritto:
> >
> > Hi,
> >
> >
> > Hi,
> >
> >
> > For a script I am working on, I am looking for a way to select a X number
> > of raster cells and their values into a numpy array. I can create a layer
> > with r.random, and read in that layer into a numpy array, but I rather
> > avoid having to read in the whole raster layer. I can also from within
> the
> > script run r.random  to generate a raster layer, r.stats to export the
> > resulting raster layer as a text file (with n flag), and than read in the
> > text file in Python. But I wonder if there is not a more direct way to
> > accomplish this..
> >
> >
> > You can read col and row from GRASS Region and use random python function
> > to calculate random x and y and later query a pygrass raster object
> >
>
>
> Thanks. And what if I have a mask or null values in the target raster.
>
>
> >
> > Cheers,
> >
> > Paulo
> >
> >
> > Cheers
> > Luca
>
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