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Re: aggregate pixel values within shapes or another raster [message #69512 is a reply to message #69391]

Mon, 18 January 2010 00:06

wita
Messages: 43
Registered: January 2005

Member

Dear Itiseva,

Have a look at: ftp://sc:image1@ftp.alterra.nl/pub/adewit/cgi_zonal_stats.pr o

It is basically as simple as:

result = cgi_zonal_stats(zones, data)

Results is a structure which contains the zone_id, mean, count, stdev
and median of the values in 'data' (each layer in your time-series)
for each unique zone in 'zones' (your 25km grid). A requirement is
that 'zones' and 'data' are on the same grid, so resample your 25km
grid to your 1km data grid.

The function leverages the power of HISTOGRAM module by looping over
the reverse indices returned by HISTOGRAM and is therefore maybe
faster then David's solution. Moreover, my routine can aggregate data
over arbitrary shaped zoned and not just within kernel.

My guess is that this is exactly what you need.

Hope this helps

Allard

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[Message index]

		aggregate pixel values within shapes or another raster By: ivitseva on Thu, 14 January 2010 01:54
		Re: aggregate pixel values within shapes or another raster By: wita on Mon, 18 January 2010 00:06

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