[GRASS-user] areas with no centroid

[Helmut Kudrnovsky]

Dave Roberts wrote
> After editing a map with wxgui I ended up with 39 areas and 38 
> centroids.  How do I find and delete the area with no centroid?
> 
> I have tried many combinations of v.info, v.category, v.to.db, and 
> visualizing with d.vect.  If I use v.clean tool=rmarea with slowly 
> increasing thresholds it gets rid of an area I want before it finds the 
> one I don't so I don't think it's a sliver.
> 
> GRASS GIS 7.3.svn > v.info demo
>   . . .
> Number of points:       0           Number of centroids: 38 
> Number of lines:        0           Number of boundaries: 112
> Number of areas:       39           Number of islands:    19
>   . . .
> GRASS GIS 7.3.svn > v.category demo op=report
> Layer/table: 1/demo
> type       count        min        max
> point          0          0          0
> line           0          0          0
> boundary       0          0          0
> centroid      38          1         75
> area           0          0          0
> face           0          0          0
> kernel         0          0          0
> all           38          1         75
> 
> Thanks, Dave
> -- 
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d. vect has following option :

cat: Display category numbers of features

try to display the cat info for the polygones to check where the centroid is
missing. 

have then a look at v.extract and extract only these polygones you need.

HTH 



-----
best regards
Helmut
--
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