[GRASS-user] Not matching categories/line IDs

Johannes Radinger johannesradinger at gmail.com
Thu Sep 13 01:50:15 PDT 2018

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

v.category input=Ebro_river_vector_poly_clean_tmp at Ebro2_alien_spread
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)

So, is it 804,799 or 803??

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).

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