#1823: v.clean -rmdup: eliminate identical categories
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Reporter: Nik | Owner: grass-dev@…
Type: enhancement | Status: new
Priority: major | Milestone: 7.0.0
Component: Vector | Version: unspecified
Keywords: v.clean, rmdupl | Platform: MSWindows 7
Cpu: x86-64 |
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Comment(by mmetz):
Replying to [ticket:1823 Nik]:
> when v.clean with the tool rmdup is used currently there is no
possibility to remove identical categories automatically.
If there are no identical categories in the input, there are also no
identical categories in the output. If two different lines have identical
coordinates and identical categories, one line is removed and the
categories are not changed (no duplicate identical categories). IOW, there
is no need to eliminate identical categories because the output geometry
does (should) not have several identical categories.
> and it would be also very helpful if I could decide to eliminate either
the first category or the second automatically in case of the categories
are different.
What would be possible is to decide whether only the categories of the
first geometry encountered are used or all categories of all found
duplicates. Discriminating between first and second geometry does not make
sense because there is no inherent logical order of geometries.
The purpose of `v.clean` is to perform topological cleaning of geometries.
Cleaning of categories, say, if a geometry has multiple categories in one
layer, keep only the unique category if exist, would be a task for
`v.category`.
>
> attachment with demo-shapefile
BTW, the projection info says it's in latlon, but the coordinates seem to
be meters or feet, definitively not degrees:
{{{
ogrinfo -so temp2 temp2
INFO: Open of `temp2'
using driver `ESRI Shapefile' successful.
Layer name: temp2
Geometry: Line String
Feature Count: 2
Extent: (459162.929850, 5312217.737961) - (461755.377824, 5314632.492825)
}}}
After removing duplicates, the resulting line has two categories, 1 and 2
in layer 1, thus no identical categories.
Markus M
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Ticket URL: <http://trac.osgeo.org/grass/ticket/1823#comment:2>
GRASS GIS <http://grass.osgeo.org>