Percent Difference

[DON EBERT]

Use this formula in r.mapcalc

percentmap = ((raster1 - raster2)*100)/raster1

This will output a map with percent values (i.e., 50 = 50%).

Don Ebert
Research Associate
National Biological Service
Cooperative Research Unit
University of Nevada - Las Vegas

On Fri, 12 Apr 1996, Robert Tetrault wrote:

> Dear GRASS users,
> 
> How can I use mapcalc to get a percent difference between two raster maps?  I
 can get r.mapcalc to "not be confused" but the resulting raster map is just 1'
s and 0's.  Am I lost in non-floating point land?  Is there a way around this?
> 
> Thanks in advance!
>