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List:       grass-dev
Subject:    [GRASS-dev] r.series: threshold/count method?
From:       Markus Neteler <neteler () osgeo ! org>
Date:       2009-08-28 20:47:41
Message-ID: 86782b610908281347m51387b27o1335af029a7a0008 () mail ! gmail ! com
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Hi,

it would be ideal to have a new threshold/count method in r.series.
Example: I am calculating growing degree days (accumulated temperatures
over one year, [1]) and want to know at which day of year (count) this
happens. Input would be 365 growing degree days maps, parameters
a threshold value (e.g. 440 for insect moulting) and the result a
count value per pixel which corresponds to the map number which
I gave as input (which is the day of year DOY in this case).

Would that be hard to implement? A bit of rounding/epsilon will be
involved to match the requested threshold since the input maps
are typically FP maps.

I can imagine more use cases: first frost day in autumn (theshold -0.1°C
or so), input daily minimum temperature maps and more...

Markus

[1] http://en.wikipedia.org/wiki/Growing_degree_day
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