[GRASS-user] Temporal Analysis

[Dylan Beaudette]

On Monday 07 June 2010, Nikos Dumakis wrote:
> Thank you Martin.
>
> I realized that one of the functions that I need, (counter of values bellow
> a certain threshold) is not available in r.series. Do you know, or do you
> have any suggestion, how to perform this?
> Thanks
>
> Best regards
> Nikos

Hi Nikos,

I can't seem to find it right now, but there was a discussion a while back 
regarding user-defined functions for r.series. I don't think anything came 
out of it, but one of the Martins or Markus' (I think) was able to put some 
nice working into a more consolidated stats library. Others may recall more 
details.

The basic premise: implement a mechanism by which a vector (i.e. the array of 
values defined by a single cell but sliced through a time series of rasters) 
could be passed to an R function, python function, etc. that would do its 
work and return a scalar to GRASS. This seems like it would be hard to 
implement, but would add tremendous flexibility to time series analysis. 

Another approach might be to use the 'raster' package for R. 

Cheers,
Dylan


> On Mon, Jun 7, 2010 at 1:12 PM, Martin Wegmann <
>
> martin.wegmann at uni-wuerzburg.de> wrote:
> > Hello Nikos,
> >
> > just give r.series a try.
> >
> > regards, Martin
> >
> > On Montag, 7. Juni 2010 14:06:17 Nikos Dumakis wrote:
> > > Greetings
> > >
> > >
> > > I have to do some simple-statistical TEMPORAL analysis between a long
> > > data-series. I mean, I have do some temporal average for each pixel,
> > > minimum and max. Instead of doing this statistical- analysis for all
> > > pixels in an image, I have to do this analysis for each image-pixel
> > > along its temporal series.
> > >
> > > Is there any function to do this? Or as anyone tried ?
> > > Thanks
> > > Nikos
> >
> > --
> > Dr. Martin Wegmann
> >
> > University of Wuerzburg
> > Institute of Geography
> > Department of Remote Sensing
> > Remote Sensing and Ecosystem Research
> > Am Hubland
> > 97074 Wuerzburg, Germany
> > @
> > German Aerospace Center (DLR)
> > German Remote Sensing Data Center (DFD)
> >
> > Phone:  +49-(0)931-31-83446
> > Fax:       +49-(0)931-31-84961
> > Email:  martin.wegmann at uni-wuerzburg.de
> > url: http://www.remote-sensing.uni-wuerzburg.de
> > url: http://www.dlr.de/caf
> > url: http://www.global-change-ecology.de



-- 
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341