[GRASS-dev] Re: [GRASS-user] How can I find average/maximum raster values within a vector area?

On 02/08/07 06:59, David Finlayson wrote:

Forgot to CC grass list

On 8/1/07, David Finlayson <dfinlayson@usgs.gov> wrote:

I think you want the command r.statistics. You will need to convert
your administrative areas vector map into a raster map where each area
has a unique ID. Then run r.statistics on the pollution map using the
administrative areas raster as the cover. This tool builds a database
table with the min,max avg, etc statistics of pollution for each area
id.

How difficult would it be to create a module 'v.statistics' which would skip the step of converting the cover to raster ?

Moritz

George,
you could also use v.rast.stats to compute
pollution statistics for the administrative
areas. See [1] for more details.

Daniel.

[1] http://grass.itc.it/gdp/html_grass63/v.rast.stats.html

Moritz Lennert wrote:

On 02/08/07 06:59, David Finlayson wrote:

Forgot to CC grass list

On 8/1/07, David Finlayson <dfinlayson@usgs.gov> wrote:

I think you want the command r.statistics. You will need to convert
your administrative areas vector map into a raster map where each area
has a unique ID. Then run r.statistics on the pollution map using the
administrative areas raster as the cover. This tool builds a database
table with the min,max avg, etc statistics of pollution for each area
id.

How difficult would it be to create a module 'v.statistics' which would skip the step of converting the cover to raster ?

Moritz

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Many thanks to you both.

v.rast.stats looks perfect – it’s churning away as I write…

G

On 2 Aug 2007, at 09:52, Daniel McInerney wrote:

George,
you could also use v.rast.stats to compute
pollution statistics for the administrative
areas. See [1] for more details.

Daniel.

[1] http://grass.itc.it/gdp/html_grass63/v.rast.stats.html

Moritz Lennert wrote:

On 02/08/07 06:59, David Finlayson wrote:

Forgot to CC grass list

On 8/1/07, David Finlayson <dfinlayson@usgs.gov> wrote:

I think you want the command r.statistics. You will need to convert
your administrative areas vector map into a raster map where each area
has a unique ID. Then run r.statistics on the pollution map using the
administrative areas raster as the cover. This tool builds a database
table with the min,max avg, etc statistics of pollution for each area
id.

How difficult would it be to create a module ‘v.statistics’ which would skip the step of converting the cover to raster ?

Moritz


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George MacKerron / 020 7870 7509

Another approach is to use a tool called Starspan. It works with any GDAL/OGR
datasource - including GRASS raster and vector files.

cheers,
Dylan

On Thursday 02 August 2007 02:21, George MacKerron wrote:

Many thanks to you both.

v.rast.stats looks perfect -- it's churning away as I write...

G

On 2 Aug 2007, at 09:52, Daniel McInerney wrote:
> George,
> you could also use v.rast.stats to compute
> pollution statistics for the administrative
> areas. See [1] for more details.
>
> Daniel.
>
> [1] http://grass.itc.it/gdp/html_grass63/v.rast.stats.html
>
> Moritz Lennert wrote:
>> On 02/08/07 06:59, David Finlayson wrote:
>>> Forgot to CC grass list
>>>
>>> On 8/1/07, David Finlayson <dfinlayson@usgs.gov> wrote:
>>>> I think you want the command r.statistics. You will need to convert
>>>> your administrative areas vector map into a raster map where
>>>> each area
>>>> has a unique ID. Then run r.statistics on the pollution map
>>>> using the
>>>> administrative areas raster as the cover. This tool builds a
>>>> database
>>>> table with the min,max avg, etc statistics of pollution for each
>>>> area
>>>> id.
>>
>> How difficult would it be to create a module 'v.statistics' which
>> would skip the step of converting the cover to raster ?
>>
>> Moritz
>>
>> _______________________________________________
>> grassuser mailing list
>> grassuser@grass.itc.it
>> http://grass.itc.it/mailman/listinfo/grassuser

--
George MacKerron / 020 7870 7509