[GRASS-user] GRASS-way to delete points from a map and attribute table

GRASS GRASS user
1

Hi,

what would be the most GRASS-like way to delete several points from a points vector map.

I know the specific cats of the points I would like to delete (10 of 200000) and I want to delete the points from the map and, of course, also from the corresponding attribute table. I already tried v.edit but here the points are not deleted from the attribute table. I could also use v.extract with the reverse flag, however this requires to define a new output map (which I would like to avoid if possible). Any straight forward way in GRASS?

/Johannes

2

Did you try v.edit:

https://grass.osgeo.org/grass72/manuals/v.edit.html

Cheers

Stefan

···

Hi,

what would be the most GRASS-like way to delete several points from a points vector map.

I know the specific cats of the points I would like to delete (10 of 200000) and I want to delete the points from the map and, of course, also from the corresponding attribute table. I already tried v.edit but here the points are not deleted from the attribute table. I could also use v.extract with the reverse flag, however this requires to define a new output map (which I would like to avoid if possible). Any straight forward way in GRASS?

/Johannes

3

Dear Stefan,
thanks for the tip, but as said I tried already v.edit but somehow this tools does not modify the attribute table (or do I miss something here?)
/Johannes

···

On Thu, Nov 9, 2017 at 10:10 AM, Stefan Blumentrath <Stefan.Blumentrath@nina.no> wrote:

Did you try v.edit:

https://grass.osgeo.org/grass72/manuals/v.edit.html

Cheers

Stefan

From: grass-user [mailto:grass-user-bounces@lists.osgeo.org] On Behalf Of Johannes Radinger
Sent: torsdag 9. november 2017 10.04
To: GRASS user list <grass-user@lists.osgeo.org>
Subject: [GRASS-user] GRASS-way to delete points from a map and attribute table

Hi,

what would be the most GRASS-like way to delete several points from a points vector map.

I know the specific cats of the points I would like to delete (10 of 200000) and I want to delete the points from the map and, of course, also from the corresponding attribute table. I already tried v.edit but here the points are not deleted from the attribute table. I could also use v.extract with the reverse flag, however this requires to define a new output map (which I would like to avoid if possible). Any straight forward way in GRASS?

/Johannes

4

So, removing records from the attribute table would be a job for db.execute of db.select I guess…

···

Dear Stefan,

thanks for the tip, but as said I tried already v.edit but somehow this tools does not modify the attribute table (or do I miss something here?)

/Johannes

On Thu, Nov 9, 2017 at 10:10 AM, Stefan Blumentrath <Stefan.Blumentrath@nina.no> wrote:

Did you try v.edit:

https://grass.osgeo.org/grass72/manuals/v.edit.html

Cheers

Stefan

From: grass-user [mailto:grass-user-bounces@lists.osgeo.org] On Behalf Of Johannes Radinger
Sent: torsdag 9. november 2017 10.04
To: GRASS user list <grass-user@lists.osgeo.org>
Subject: [GRASS-user] GRASS-way to delete points from a map and attribute table

Hi,

what would be the most GRASS-like way to delete several points from a points vector map.

I know the specific cats of the points I would like to delete (10 of 200000) and I want to delete the points from the map and, of course, also from the corresponding attribute table. I already tried v.edit but here the points are not deleted from the attribute table. I could also use v.extract with the reverse flag, however this requires to define a new output map (which I would like to avoid if possible). Any straight forward way in GRASS?

/Johannes

5

Indeed, finally I also used a combination of v.edit to remove the point from the map and db.execute (“DELETE FROM my_point_map WHERE cat IN (1,2,3)”) to delete the entries from the attribute table.

/Johannes

···

On Thu, Nov 9, 2017 at 10:27 AM, Stefan Blumentrath <Stefan.Blumentrath@nina.no> wrote:

So, removing records from the attribute table would be a job for db.execute of db.select I guess…

From: Johannes Radinger [mailto:johannesradinger@gmail.com]
Sent: torsdag 9. november 2017 10.17
To: Stefan Blumentrath <Stefan.Blumentrath@nina.no>
Cc: GRASS user list <grass-user@lists.osgeo.org>
Subject: Re: [GRASS-user] GRASS-way to delete points from a map and attribute table

Dear Stefan,

thanks for the tip, but as said I tried already v.edit but somehow this tools does not modify the attribute table (or do I miss something here?)

/Johannes

On Thu, Nov 9, 2017 at 10:10 AM, Stefan Blumentrath <Stefan.Blumentrath@nina.no> wrote:

Did you try v.edit:

https://grass.osgeo.org/grass72/manuals/v.edit.html

Cheers

Stefan

From: grass-user [mailto:grass-user-bounces@lists.osgeo.org] On Behalf Of Johannes Radinger
Sent: torsdag 9. november 2017 10.04
To: GRASS user list <grass-user@lists.osgeo.org>
Subject: [GRASS-user] GRASS-way to delete points from a map and attribute table

Hi,

what would be the most GRASS-like way to delete several points from a points vector map.

I know the specific cats of the points I would like to delete (10 of 200000) and I want to delete the points from the map and, of course, also from the corresponding attribute table. I already tried v.edit but here the points are not deleted from the attribute table. I could also use v.extract with the reverse flag, however this requires to define a new output map (which I would like to avoid if possible). Any straight forward way in GRASS?

/Johannes

6

IMHO it would be helpful to add a flag to v.edit to also delete the database entries when tool=delete.
In general use, when I delete a feature, I don’t expect to leave orphaned entries in the attribute table.

···

On 11/09/2017 12:25 PM, Johannes Radinger wrote:

Indeed, finally I also used a combination of v.edit to remove the point from the map and db.execute (“DELETE FROM my_point_map WHERE cat IN (1,2,3)”) to delete the entries from the attribute table.

/Johannes

On Thu, Nov 9, 2017 at 10:27 AM, Stefan Blumentrath <Stefan.Blumentrath@nina.no> wrote:

So, removing records from the attribute table would be a job for db.execute of db.select I guess…

From: Johannes Radinger [mailto:johannesradinger@gmail.com]
Sent: torsdag 9. november 2017 10.17
To: Stefan Blumentrath <Stefan.Blumentrath@nina.no>
Cc: GRASS user list <grass-user@lists.osgeo.org>
Subject: Re: [GRASS-user] GRASS-way to delete points from a map and attribute table

Dear Stefan,

thanks for the tip, but as said I tried already v.edit but somehow this tools does not modify the attribute table (or do I miss something here?)

/Johannes

On Thu, Nov 9, 2017 at 10:10 AM, Stefan Blumentrath <Stefan.Blumentrath@nina.no> wrote:

Did you try v.edit:

https://grass.osgeo.org/grass72/manuals/v.edit.html

Cheers

Stefan

From: grass-user [mailto:grass-user-bounces@lists.osgeo.org] On Behalf Of Johannes Radinger
Sent: torsdag 9. november 2017 10.04
To: GRASS user list <grass-user@lists.osgeo.org>
Subject: [GRASS-user] GRASS-way to delete points from a map and attribute table

Hi,

what would be the most GRASS-like way to delete several points from a points vector map.

I know the specific cats of the points I would like to delete (10 of 200000) and I want to delete the points from the map and, of course, also from the corresponding attribute table. I already tried v.edit but here the points are not deleted from the attribute table. I could also use v.extract with the reverse flag, however this requires to define a new output map (which I would like to avoid if possible). Any straight forward way in GRASS?

/Johannes

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-- 
Micha Silver
Ben Gurion Univ.
Sde Boker, Remote Sensing Lab
cell: +972-523-665918
7

On Fri, Nov 10, 2017 at 10:06 AM, Micha Silver <tsvibar@gmail.com> wrote:

IMHO it would be helpful to add a flag to v.edit to also delete the database entries when tool=delete.
In general use, when I delete a feature, I don’t expect to leave orphaned entries in the attribute table.

It’s not that simple, you would also need to check if this entry in the attribute table, i.e. this category value, is not used by any of the other geometries left (different geometries can share the same category value and attributes).

Best would be a new library function that prunes a table, removing all unused entries, something like Vect_prune_table().

Markus M

On 11/09/2017 12:25 PM, Johannes Radinger wrote:

Indeed, finally I also used a combination of v.edit to remove the point from the map and db.execute (“DELETE FROM my_point_map WHERE cat IN (1,2,3)”) to delete the entries from the attribute table.

/Johannes

On Thu, Nov 9, 2017 at 10:27 AM, Stefan Blumentrath <Stefan.Blumentrath@nina.no> wrote:

So, removing records from the attribute table would be a job for db.execute of db.select I guess…

From: Johannes Radinger [mailto:johannesradinger@gmail.com]
Sent: torsdag 9. november 2017 10.17
To: Stefan Blumentrath <Stefan.Blumentrath@nina.no>
Cc: GRASS user list <grass-user@lists.osgeo.org>
Subject: Re: [GRASS-user] GRASS-way to delete points from a map and attribute table

Dear Stefan,

thanks for the tip, but as said I tried already v.edit but somehow this tools does not modify the attribute table (or do I miss something here?)

/Johannes

On Thu, Nov 9, 2017 at 10:10 AM, Stefan Blumentrath <Stefan.Blumentrath@nina.no> wrote:

Did you try v.edit:

https://grass.osgeo.org/grass72/manuals/v.edit.html

Cheers

Stefan

From: grass-user [mailto:grass-user-bounces@lists.osgeo.org] On Behalf Of Johannes Radinger
Sent: torsdag 9. november 2017 10.04
To: GRASS user list <grass-user@lists.osgeo.org>
Subject: [GRASS-user] GRASS-way to delete points from a map and attribute table

Hi,

what would be the most GRASS-like way to delete several points from a points vector map.

I know the specific cats of the points I would like to delete (10 of 200000) and I want to delete the points from the map and, of course, also from the corresponding attribute table. I already tried v.edit but here the points are not deleted from the attribute table. I could also use v.extract with the reverse flag, however this requires to define a new output map (which I would like to avoid if possible). Any straight forward way in GRASS?

/Johannes

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–
Micha Silver
Ben Gurion Univ.
Sde Boker, Remote Sensing Lab
cell: +972-523-665918

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