[GRASS-user] How to find the second largest value in a series of rasters.

Marcello Gorini gorini at gmail.com
Fri Dec 9 06:59:06 EST 2011


> I have to find the maximum value for each cell in a series
> > of rasters and generate both a maximum value map and a
> > categorical map with the raster number which contains the
> > maximum value.

> see also:
> http://grass.osgeo.org/wiki/Time_series#Common_legends_for_many_raster_maps
> it sounds like you have done something similar already, but
> maybe you could adapt it somehow, or it is faster.
> I think you'll have to use g.copy + r.null (or better r.reclass)
> to hide the highest values.
Thanks for the ideas. I still haven't quite figured out how to do it
without a loop, but I will keep trying.

Anyway, I found very useful this kind of expression:

 for MAP in `g.mlist rast pattern=$MAP_PATTERN` ; do
   eval `r.info -r $MAP`

I didn't know it was possible. Thanks.

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