[GRASS-user] percentage of class in raster within polygons

[Margherita Di Leo]

Hi,

I have to calculate the percentage of given class of a raster within the
polygons given in a vector (a regular grid). Since I'm dealing with large
files and operations repeated in a chain, i should be focusing on what is
the optimal (fastest) option to do that. I could vectorize the raster and
use v.overlay and v.to.db, or using v.rast.stats i can count out the number
of cells (should i use number for that or sum?) and then divide per  area
of the grid. Any better idea?

Thank you in advance

-- 
Best regards,

Dr. Margherita DI LEO
Scientific / technical project officer

European Commission - DG JRC
Institute for Environment and Sustainability (IES)
Via Fermi, 2749
I-21027 Ispra (VA) - Italy - TP 261

Tel. +39 0332 78 3600
margherita.di-leo at jrc.ec.europa.eu

Disclaimer: The views expressed are purely those of the writer and may not
in any circumstance be regarded as stating an official position of the
European Commission.
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