[GRASS-dev] removing small multiple polygons created by r.stream.basin + r.to.vect

[Markus Neteler]

On Mon, Apr 9, 2012 at 4:25 PM, Margherita Di Leo
<dileomargherita at gmail.com> wrote:
> Ciao Markus,
>
> On Mon, Apr 9, 2012 at 3:47 PM, Markus Neteler <neteler at osgeo.org> wrote:
>>
>> Wouldn't it be better to remove them with v.clean and rmarea to avoid
>> holes?
>
>
> just tried with:
>
>
>         grass.run_command('v.clean', input = v_basins,
>                                      output = v_basin,
>                                      type = 'area',
>                                      tool = 'rmarea',
>                                      thresh = 1,     # I also tried 10
>                                      overwrite = True)
>
> Maybe I do something wrong, but this way I can't get rid of small polygons,

what is exactly happening? Nothing or some are removed?

> and, in addiction, I need to set the threshold parameter, which I'm not sure
> to be suitable for all cases...

I wanted to suggest to run quartile statistics (extended stats in v.univar) on
an "area" column (if needed, add with v.to.db). But I realized that it only
supports extended statistics on point data :( No idea why this limitation...
So I thought to suggest the 1st quartile as threshold.

Maybe someone else has an idea?

Markus