[GRASS-user] v.select incredibly slow

Uwe Fischer gisfisch at t-online.de
Sat Mar 27 06:58:01 PDT 2021


Hello list,

I have trouble selecting line features using their location compared to a
polygon layer using v.select. The line features I want to select from are
parcel borders, and the polygon layer is made up of tubular-shaped buffers
around municipal borders. I need to find the parcel borders which are inside
this buffer.

The command line in a Python script I use is:

grass.run_command('v.select', ainput='temp5', atype='line', binput='buff',
blayer=1, btype='area', output='grenz', operator='within', overwrite=True)

The process starts, but it runs incredibly slow (> 15 min) and it brings not
the desired result (but trash data). When I start it in the GRASS ui, it
also works very very slow.

I have only about 2000 parcel borders, so it cannot be a problem of too much
features. Furthermore, the exact same selection task is processed in QGIS 3
in a second with perfect results.

I used v.build on both maps before v.select, but it does not help.

I would like to perform it in GRASS because it is part of a bigger data
preparation script which makes my work a lot easier. So I need to integrate
it here rather than selecting in QGIS manually.

Thanks for help,

 

Uwe

 

 

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