[GRASS-user] categories in raster map

[FAROUX STEPHANIE]

Moritz Lennert wrote:
> On 26/02/09 13:34, FAROUX STEPHANIE wrote:
>> FAROUX STEPHANIE wrote:
>>> Moritz Lennert wrote:
>>>> On 26/02/09 11:47, FAROUX STEPHANIE wrote:
>>>>> Hello,
>>>>> I see the function r.cats which allows to read categories of a 
>>>>> raster map, but how can i define these attributes? Should i pass 
>>>>> by a vector map? In the database menu, it doesn't seem possible to 
>>>>> add a table for a raster map.
>>>>
>>>> Raster maps have categories and labels. Categories have to be 
>>>> numerical, labels can be anything. Each pixel needs to have a 
>>>> category value (or NULL) and optionally you can have one (and only 
>>>> one) label per category value.
>>>>
>>>> BTW, r.cats is now replaced by r.category.
>>>>
>>>> If you want to link a cell with many attributes, you will have to 
>>>> use vector grids (v.mkgrid or r.to.vect as you suggestà).
>>>>
>>>> Moritz
>>>>
>>> Thank you. And how do you put labels on categories please?
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>> I use r.reclass that's it?
>
> No, r.reclass "changes" category values, not labels.
>
> I think it would be better if you explained a bit more clearly what 
> you want to do, i.e. what do you have and what would you like to have.
>
> Normally, r.category seems to be what you are looking for, using the 
> rules= option.
>
> I do see that the man page might not be particularly clear on its 
> usage (the Description part only mentions printing, not managing 
> labels and the part on dynamic labels is a bit cryptic). But the 
> section "Input from a file" should give you what you need.
>
> Moritz
>
Ok. I see it in the manual page of the 6.5 version.
Actually i work with the 6.2 version (i'm at office and i haven't 
"control" on the installed version) and i think r.cats doesn't have this 
option. But with r.reclass i achieved.
Here i have a map with integer categories values; i want to recode these 
categories but keep old values as labels.
Stéphanie