[GRASS-user] Replace 0 by NULL in categorial raster map

[Moritz Lennert]

On 02/03/12 15:56, Johannes Radinger wrote:
> Just for my personal interest two questions: 1) What if I want to
> replace the category "0" with NULL (not the values 0)

Category 0 = value 0.

Raster values in GRASS are called categorie values.

Or maybe I don't understand what you mean ?

> 2) What would be the correct module if I want to assign another
> category than NULL to certain values? Is hat module r.category? And
> how can that be used in pyhton (how are the rules supplied)? Eg.
> assign all values greater than 0 to 1 all other values NULL.

If you have a integer values (CELL), then r.reclass.

If you have floating point values, generally r.recode is more 
appropriate (or just multiply your floating point map by the appropriate 
number to make it integer).

Moritz