[GRASS-user] Determining maximum value of attributes where areas are overlapping in imported vector layer

[Rainer M Krug]

On Mon, Jul 7, 2008 at 6:19 PM, Markus Neteler <neteler at osgeo.org> wrote:
> On Mon, Jul 7, 2008 at 6:11 PM, Rainer M Krug <r.m.krug at gmail.com> wrote:
>> Hi
>>
>> I am back with a problem of imported shape files:
>>
>> I have imported a shape file and it contains several areas where
>> polygons are overlapping. After I managed to obtain the number of
>> overlapping polygons and exported it to a raster layer
>> (http://grass.osgeo.org/wiki/Vector_Overlapping_Areas), I would now
>> need the maximum value of an attribute column for this areas.
>>
>> Any ideas how I can achieve this?
>
> You can use 'db.select':
>
> echo "SELECT max(N1) FROM lidar2" | db.select
> max(N1)
> 512834.76000000000931

Sorry for not being spoecific enough - I want the maximum values as
ributes in an attribute table.
As far as I can see, this just gives me the maximum value of the whole
table - but I need it spatially, i.e. for each area which is
overlapping, the maximum value.

>
> Markus
>



-- 
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
Biology, UCT), Dipl. Phys. (Germany)

Plant Conservation Unit
Department of Botany
University of Cape Town
Rondebosch 7701
South Africa