#!/bin/sh
#
# This program is Free Software under the GNU GPL (>=v2).
# calculate univariate statistics for GRASS raster data
#
# Cited from the book:
#   Markus Neteler and Helena Mitasova:
#   Open Source GIS: A GRASS GIS Approach.
#   Kluwer Academic Publishers, Boston, Dordrecht, 464 pp,
#   ISBN: 1-4020-7088-8, http://mpa.itc.it/grasstutor/

if test "$GISBASE" = ""; then
echo "You must be in GRASS to run this program."
exit
fi

MAP=$1
r.stats -1 $MAP | awk 'BEGIN {sum = 0.0 ; sum2 = 0.0}
NR == 1{min = $2 ; max = $1}
       {sum += $1 ; sum2 += $1 * $1 ; N++}
       {
        if ($1 > max) {max = $1} 
        if ($1 < min) {min = $1}          
       }
END{
print "Number of raster data samples N =",N
print "Minimum value      MIN  =",min     
print "Maximum value      MAX  =",max     
print "Variation          v    =",(max - ((min * -1) * -1))  
print "Mean               MEAN =",sum / N  
print "Variance           S2   =",(sum2 - sum * sum / N) / N  
print "Standard deviation S    =",sqrt((sum2 - sum * sum/N) / N)
print "Variation coeffic. V    =",100*(sqrt((sum2 - sum*sum/N)/N))/(sum/N)
}'