[GRASS-user] count points within poly and update column

GRASS GRASS user
1

Hi,

I need to count the number of points that falls within a set of polygons, and add this number as a column in the table associated with the polygon.How can I do that?

Thanks,
madi

···

Best regards,

Dr. Margherita DI LEO
Scientific / technical project officer

European Commission - DG JRC
Institute for Environment and Sustainability (IES)
Via Fermi, 2749
I-21027 Ispra (VA) - Italy - TP 261

Tel. +39 0332 78 3600
margherita.di-leo@jrc.ec.europa.eu

Disclaimer: The views expressed are purely those of the writer and may not in any circumstance be regarded as stating an official position of the European Commission.

2

Margherita Di Leo:

Hi,

I need to count the number of points that falls within a set of polygons,
and add this number as a column in the table associated with the
polygon.How can I do that?

Madi,

that was a somewhat cumbersome task in the past. Not anymore though,
please see: <http://grass.osgeo.org/grass70/manuals/v.vect.stats.html&gt;\.

Nikos

3

Hey Nikos!

···

On Fri, Apr 17, 2015 at 10:22 PM, Nikos Alexandris <nik@nikosalexandris.net> wrote:

Margherita Di Leo:

Hi,

I need to count the number of points that falls within a set of polygons,
and add this number as a column in the table associated with the
polygon.How can I do that?

Madi,

that was a somewhat cumbersome task in the past. Not anymore though,
please see: <http://grass.osgeo.org/grass70/manuals/v.vect.stats.html>.

Thank you very much! I have been looking here http://grass.osgeo.org/grass71/manuals/vectorintro.html and http://grass.osgeo.org/grass71/manuals/topic_statistics.html and in the wiki but could find no reference. I’m adding a FAQ in the wiki and keywords in the documentation pages.

Thanks again!
madi

–

Best regards,

Dr. Margherita DI LEO
Scientific / technical project officer

European Commission - DG JRC
Institute for Environment and Sustainability (IES)
Via Fermi, 2749
I-21027 Ispra (VA) - Italy - TP 261

Tel. +39 0332 78 3600
margherita.di-leo@jrc.ec.europa.eu

Disclaimer: The views expressed are purely those of the writer and may not in any circumstance be regarded as stating an official position of the European Commission.

4

On Fri, Apr 17, 2015 at 4:34 PM, Margherita Di Leo <diregola@gmail.com>
wrote:

Hey Nikos!

On Fri, Apr 17, 2015 at 10:22 PM, Nikos Alexandris <
nik@nikosalexandris.net> wrote:

Margherita Di Leo:

> Hi,
>
> I need to count the number of points that falls within a set of
polygons,
> and add this number as a column in the table associated with the
> polygon.How can I do that?

Madi,

that was a somewhat cumbersome task in the past. Not anymore though,
please see: <http://grass.osgeo.org/grass70/manuals/v.vect.stats.html&gt;\.

Thank you very much! I have been looking here
http://grass.osgeo.org/grass71/manuals/vectorintro.html and
http://grass.osgeo.org/grass71/manuals/topic_statistics.html and in the
wiki but could find no reference. I'm adding a FAQ in the wiki and keywords
in the documentation pages.

Very good. Additionally, v.vect.stats is really awesome because it creates

the columns for the data automatically (other modules usually requires you
to create it beforehand).

BTW, the hard way would be to do it through export to xyz/csv, import using
binning and raster-vector statistics.

Thanks again!

madi

--
Best regards,

Dr. Margherita DI LEO
Scientific / technical project officer

European Commission - DG JRC
Institute for Environment and Sustainability (IES)
Via Fermi, 2749
I-21027 Ispra (VA) - Italy - TP 261

Tel. +39 0332 78 3600
margherita.di-leo@jrc.ec.europa.eu

Disclaimer: The views expressed are purely those of the writer and may not
in any circumstance be regarded as stating an official position of the
European Commission.

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

5

On Apr 17, 2015 10:34 PM, “Margherita Di Leo” <diregola@gmail.com> wrote:

I’m adding a FAQ in the wiki

Note that there was already an entry at

http://grasswiki.osgeo.org/wiki/Count_points_in_polygon#Geometry_based_solution

Best
Markus

and keywords in the documentation pages.

Thanks again!
madi

–
Best regards,

Dr. Margherita DI LEO
Scientific / technical project officer

European Commission - DG JRC
Institute for Environment and Sustainability (IES)
Via Fermi, 2749
I-21027 Ispra (VA) - Italy - TP 261

Tel. +39 0332 78 3600
margherita.di-leo@jrc.ec.europa.eu

Disclaimer: The views expressed are purely those of the writer and may not in any circumstance be regarded as stating an official position of the European Commission.

grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

6

On Sun, Apr 19, 2015 at 9:05 AM, Markus Neteler <neteler@osgeo.org> wrote:

On Apr 17, 2015 10:34 PM, "Margherita Di Leo" <diregola@gmail.com> wrote:
> I'm adding a FAQ in the wiki

Note that there was already an entry at

http://grasswiki.osgeo.org/wiki/Count_points_in_polygon#Geometry_based_solution

Uops! Thank you Markus

--
Best regards,

Dr. Margherita DI LEO
Scientific / technical project officer

European Commission - DG JRC
Institute for Environment and Sustainability (IES)
Via Fermi, 2749
I-21027 Ispra (VA) - Italy - TP 261

Tel. +39 0332 78 3600
margherita.di-leo@jrc.ec.europa.eu

Disclaimer: The views expressed are purely those of the writer and may not
in any circumstance be regarded as stating an official position of the
European Commission.

7

On Sun, Apr 19, 2015 at 9:58 AM, Margherita Di Leo <diregola@gmail.com>
wrote:

On Sun, Apr 19, 2015 at 9:05 AM, Markus Neteler <neteler@osgeo.org> wrote:

On Apr 17, 2015 10:34 PM, "Margherita Di Leo" <diregola@gmail.com> wrote:
> I'm adding a FAQ in the wiki

Note that there was already an entry at

http://grasswiki.osgeo.org/wiki/Count_points_in_polygon#Geometry_based_solution

Uops! Thank you Markus

So this page

http://grasswiki.osgeo.org/wiki/Vector_count_points_within_polygon_and_update_column
should be removed. I think this operation should be performed by wiki
admins, right? I don't seem to have this option.

Thanks

--
Best regards,

Dr. Margherita DI LEO
Scientific / technical project officer

European Commission - DG JRC
Institute for Environment and Sustainability (IES)
Via Fermi, 2749
I-21027 Ispra (VA) - Italy - TP 261

Tel. +39 0332 78 3600
margherita.di-leo@jrc.ec.europa.eu

Disclaimer: The views expressed are purely those of the writer and may not
in any circumstance be regarded as stating an official position of the
European Commission.

8

On Sun, Apr 19, 2015 at 10:11 AM, Margherita Di Leo <diregola@gmail.com> wrote:

On Sun, Apr 19, 2015 at 9:05 AM, Markus Neteler <neteler@osgeo.org> wrote:

...

http://grasswiki.osgeo.org/wiki/Count_points_in_polygon#Geometry_based_solution

So this page
http://grasswiki.osgeo.org/wiki/Vector_count_points_within_polygon_and_update_column
should be removed. I think this operation should be performed by wiki
admins, right? I don't seem to have this option.

Done (in favour of the upper link).

Markus