[GRASS-user] v.rast.stats over a large vector file

[Markus Metz]

<razmjooeis at faunalia.co.uk> wrote:
>
> I managed to compile grass6.5 and the plugin.
> Now when I try to run it, it comes up with this error:
>
So far so good...

> /usr/local/grass-6.5.svn/scripts/v.rast.stats2: 350: Syntax
> error: "(" unexpected
>
I can't reproduce this in the North Carolina sample dataset, mapset user1 with
g.copy vect=boundary_county at PERMANENT,myboundary_county
v.rast.stats2 -c vector=myboundary_county at user1
raster=elev_state_500m at PERMANENT colprefix=alt

Can you?

Markus M

>
>> On Fri, Nov 26, 2010 at 12:32 PM,  <razmjooeis at faunalia.co.uk> wrote:
>>> Dear list
>>>
>>> I am trying to run v.rast.stats for a large vector file. It contains
>>> around 700000 buildings representing buildings.
>>>
>>> here is my g.region info
>>> g.region -p
>>> projection: 99 (Transverse Mercator)
>>> zone:       0
>>> datum:      osgb36
>>> ellipsoid:  airy
>>> north:      183010.45829976
>>> south:      153516.19024768
>>> west:       513122.49174945
>>> east:       555953.95182415
>>> nsres:      4.99987592
>>> ewres:      5.00017045
>>> rows:       5899
>>> cols:       8566
>>> cells:      50530834
>>>
>>> THe problem I am having is the process is extremely slow. It has done
>>> 150
>>> features out of 700000 areas after 2 hours.
>>> I need just the average raster value within each building (feature).
>>> My questions are:
>>> - Is there something I can do to speed up the process?
>>> - Is there a way just to get the average value rather than the whole set
>>> of statistical parameters (I am not even using -e option)
>>>
>> You could try v.rast.stats2 from grass-addons, it should complete in
>> less than 1 hour. When using v.rast.stats2 and grass 6.4, you also
>> need r,univar.zonal from grass-addons (not needed for grass 6.5).
>>
>> Markus M
>>
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