[GRASS-user] Not matching categories/line IDs

[Johannes Radinger]

Hi Markus,
Hi all,

I created a zipped version of a test location including one PERMANENT
mapset that includes the vector map that causes these inconsistencies
(Ebro_river_vector_poly_clean_tmp). The test location can be downloaded
from here: https://we.tl/t-eSUZqfP0TQ. I also included the initial vector
map before running the v.clean tool (Ebro_river_vector_poly_tmp). More
specifically, I am using following code:

grass.run_command("v.clean",
        overwrite=True,
        flags="c",
        input="Ebro_river_vector_poly_tmp",
        output="Ebro_river_vector_poly_clean_tmp",
        tool="break,rmdupl,rmline,rmsa,rmdangle",
        threshold="0,0,0,0,0.001")

Maybe this helps to find out what happens here.

/Johannes

On Thu, Sep 13, 2018 at 10:26 PM Markus Metz <markus.metz.giswork at gmail.com>
wrote:

>
>
> On Thu, Sep 13, 2018 at 10:50 AM Johannes Radinger <
> johannesradinger at gmail.com> wrote:
> >
> > Hi all,
> >
> > I am a little bit puzzled about the actual number of lines/categories of
> a specific vector map (river network). As discussed yesterday, the output
> of v.category with the report option provides a column 'count' which is a
> feature count. Running v.category option=report on my vector provides me
> following:
> >
> > v.category input=Ebro_river_vector_poly_clean_tmp at Ebro2_alien_spread
> option=report
> > Layer/table: 1/Ebro_river_vector_poly_clean_tmp
> > type       count        min        max
> > point          0          0          0
> > line         804          1       1053
> > ....
> >
> > This would indicate that I have 804 line features. However, using the
> tool v.info on the same vector I get following different result regarding
> the number of lines:
> > v.info map=Ebro_river_vector_poly_clean_tmp at Ebro2_alien_spread
>
> >
>  +----------------------------------------------------------------------------+
> >  | Name:            Ebro_river_vector_poly_clean_tmp
>      |
> >  ...
> >  |   Number of points:       0               Number of centroids:  0
>      |
> >  |   Number of lines:        799             Number of boundaries: 0
>      |
> > ...
> >
> > And even more puzzling, I then added a table to this vector map and the
> output of v.db.addtable is:
> > v.db.addtable map=Ebro_river_vector_poly_clean_tmp at Ebro2_alien_spread
>
> > Reading features...
> > Updating database...
> > 803 categories read from vector map (layer 1)
> > 803 categories read from vector map don't exist in selection from table
> > 803 records updated/inserted (layer 1)
>
> If there are 804 features, 2 features must have the same category value,
> resulting in 803 updates to the database
> >
> > So, is it 804,799 or 803??
>
> The output of v.info and v.category option=report must be identical with
> regard to the count of features.
> >
> > The map I am using is a polyline river network (cat=first) that has gone
> trough the tool v.clean with the options:
> break,rmdupl,rmline,rmsa,rmdangle. The number of lines and cats before the
> cleaning tool is 805 (consistent output among all tools).
> >
> > So I am wondering what happens during cleaning and how to get a clean
> map with a corresponding table that has entries for each cat, and were each
> cat represents one line feature (i.e. that the number of cats/line features
> is consistent over the multiple tools).
> >
> > Please let me know if I should share the vector map (and how, which
> format).
>
> Ideal would be a stripped down GRASS mapset with only this vector
> Ebro_river_vector_poly_clean_tmp. Exporting the vector would change the
> geometry representation and it would no longer be possible to reproduce the
> problem.
>
> Markus M
>
>
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