A couple days ago I posted the following question:
 
>I want to get some statistics that r.stats can't directly come up
>with, and I'm wondering if there is another function to do the trick.
>I have two raster maps: one has polygons defining different "landscape
>units".  The second is a crop yield "surface" from the same area.
>I want to know, for each landscape unit, not simply the total area,
>but also the mean yield, and standard deviation, etc.  So I need a
>routine that uses the landscape units map as a "mask", and calculates
>descriptive statistics from the raster values of the yield map found
>within the area of each polygon.
>
>Any suggestions?

I got several suggestions.  Thanks to those who responded.  The kinds
of suggestions and/or ideas I came up with were:

A) Get the raw statistics using r.stats, then transfer these to a 
   spreadsheet.  This suggestion misunderstands the question, in that
   I wanted a "direct" way of getting the mean and standard deviation,
   without the extra human processing.  We're looking for a single
   command line here.

B) Write a script to do the job, taking the raw data from r.stats.
   Susan Huse (sue@ced.berkeley.edu) sent me a great gawk script that
   only needs a little tweaking to do the job.  Thanks, Sue; I might
   even learn a little gawk this way.  :)

C) I am tempted to modify r.average so that it gives not only the mean,
   but also standard deviation.  A fun little exercise in GRASS programming.
   But I probably won't get around to it because ....

D) Bill Baker (BAKERWL@UWYO.EDU) has written the r.le tools, which
   do exactly what I want and much more.  Specifically, Bill assures
   me the task I want to do requires the command:

     r.le.pixel map=crop_yield sam=r reg=landscape_units att=b1,b2,b3,b4

   The r.le tools are in rle21.tar.Z in the incoming directory on the
   "moon" ftp server.  They do much more than simple stats, so much more
   that I forgot they also do these simple things.  :)  Thanks, Bill!

Tim.


