[GRASS-user] [EXTERNAL] [GRASS-dev] vector patching frustration

[Michael Barton]

Thanks Doug and Vincent.

None of this works. I vaguely remember having this same kind of road block several years back.

Nothing in v.category lets you change an existing cat value to a different value
v.in.ogr MUST add a column that MUST be named cat (all else causes an error--this is a bug) that is a series of consecutive integers from 1-n. So I cannot create a file with a cat field that matches my vector areas.

v.edit won't let you change an existing cat number AFAICT. No error but nothing changes.

Once I've imported a table using v.in.ogr, I cannot use db.drop.column to delete the cat column--even if it is not being used as a key field. This raises an error.

No way to rename a column from cat to something else (or something else to cat) unless you've already connected it to a vector map even if cat is not the key field. So I can't create an integer column to link up my lost vector area with a record in my csv file.

This simple task is just not possible in GRASS AFAICT. Or if it is possible, it can only be done by such non-obvious and convoluted means that I've yet to find a method that works in spite of asking a large number of very skilled GRASS users.

Michael
_____________________________

C. Michael Barton
Associate Director, School of Complex Adaptive Systems (https://scas.asu.edu<https://scas.asu.edu/>)
Professor, School of Human Evolution & Social Change (https://shesc.asu.edu)
Director, Center for Social Dynamics & Complexity (https://complexity.asu.edu)
Arizona State University
Tempe, AZ 85287-2701
USA

Executive Director, Open Modeling Foundation (https://openmodelingfoundation.github.io<https://openmodelingfoundation.github.io/>)
Director, Network for Computational Modeling in Social & Ecological Sciences (https://comses.net)

personal website: http://www.public.asu.edu/~cmbarton


On Mar 14, 2024, at 7:10 AM, Newcomb, Doug <doug_newcomb at fws.gov> wrote:

Have you tried a .csvt file for your .csv file? https://gdal.org/drivers/vector/csv.html<https://urldefense.com/v3/__https://gdal.org/drivers/vector/csv.html__;!!IKRxdwAv5BmarQ!dv7XjZX6-VnNpFbpXP6R1XYWkuaA4Y-gDR4RvL3bWazWUkLfURuKDMWqiBFqBS6jlNSHDKZCo02GJKjauaAJ-pCVIKD5JDc$>

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From: grass-dev <grass-dev-bounces at lists.osgeo.org<mailto:grass-dev-bounces at lists.osgeo.org>> on behalf of Michael Barton via grass-dev <grass-dev at lists.osgeo.org<mailto:grass-dev at lists.osgeo.org>>
Sent: Wednesday, March 13, 2024 7:02 PM
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Subject: [EXTERNAL] [GRASS-dev] vector patching frustration




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I am completely stymied in my attempt to do what should be a simple task. I have a map of vector areas, linked with an attribute table. I would like to patch in one more vector area, for which I have equivalent attribute information. I have tried this multiple ways and I cannot make this patch happen so that the added area has attribute info.

The closest I've come is to create and link a one line table to the new area that has exactly the same fields as the larger vector area map. The first map has 154 areas (i.e., cat=1-155). When I patch the maps and look at the resulting attribute table, I indeed see line and cat 155. But it is not linked with the patched area--which has been assigned a cat=183 for reasons I cannot fathom. The patch also renumbers my cat field to cat=2-155 from the original 1-154.

This has been made more complicated by the fact that v.in.ogr imports all columns of a *.csv as text, regardless of what is in them and assigns cat numbers starting at 1. So I can't specify an integer key field of 155 to try the linking. Nor can I change the assigned cat of the single area I am trying to patch from 1 to 155 using v.category (or anything else I can find).

I'm hoping that someone has a clever solution that I've not seen or I'll just have to do this fairly simple and straightforward vector operation in QGIS.

Michael
_____________________________
C. Michael Barton
Associate Director, School of Complex Adaptive Systems (https://scas.asu.edu<https://scas.asu.edu/>)
Professor, School of Human Evolution & Social Change (https://shesc.asu.edu<https://shesc.asu.edu/>)
Director, Center for Social Dynamics & Complexity (https://complexity.asu.edu<https://complexity.asu.edu/>)
Arizona State University
Tempe, AZ 85287-2701
USA

Executive Director, Open Modeling Foundation (https://openmodelingfoundation.github.io<https://urldefense.com/v3/__https://openmodelingfoundation.github.io/__;!!IKRxdwAv5BmarQ!dv7XjZX6-VnNpFbpXP6R1XYWkuaA4Y-gDR4RvL3bWazWUkLfURuKDMWqiBFqBS6jlNSHDKZCo02GJKjauaAJ-pCVvuAToIA$>)
Director, Network for Computational Modeling in Social & Ecological Sciences (https://comses.net<https://urldefense.com/v3/__https://comses.net/__;!!IKRxdwAv5BmarQ!dv7XjZX6-VnNpFbpXP6R1XYWkuaA4Y-gDR4RvL3bWazWUkLfURuKDMWqiBFqBS6jlNSHDKZCo02GJKjauaAJ-pCVdW6V-z8$>)

personal website: http://www.public.asu.edu/~cmbarton

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