[GRASSLIST:1813] Re: newby question

[Eric G. Miller]

On Sat, May 05, 2001 at 06:33:38PM -0400, Koos Jan Niesink wrote:
> Hello all, 
> 
> I just started using grass, but I have a little trouble finding some
> commands. I am looking for a command with which I can join two maps into
> one. I want to join to two gtopo30 maps into one. And the other command
> I am looking for is one which can cut out a certain area of a map. 

r.patch will paste rasters together.

You can use g.region to set an "area of interest", and if you really
want a subset, it's easy to use r.mapcalc as in:

GRASS ~/> echo "newmap = oldmap" | r.mapcalc

The new map will only contain parts of oldmap that fall within the
current "region" settings.  It's worth learning r.mapcalc, since you can
do alot of fairly arbitrary stuff with it (at least with rasters).

-- 
Eric G. Miller <egm2 at jps.net>