[GRASS-user] r.category value range

[Moritz Lennert]

On 04/02/15 15:51, Moritz Lennert wrote:
> On 04/02/15 15:45, Moritz Lennert wrote:
>> On 04/02/15 15:23, Markus Metz wrote:
>>> On Wed, Feb 4, 2015 at 1:14 PM, Moritz Lennert
>>> <mlennert at club.worldonline.be> wrote:
>>>> On 04/02/15 11:48, Martin Album Ytre-Eide wrote:
>>>>>
>>>>> Hello!
>>>>>
>>>>> I trying to set a label  for a range of values in  a raster.
>>>>>
>>>>> I am using r.category (grass 7.0)
>>>>>
>>>>> "r.category map=lwc_2014 separator=':' rules=lwc.rules"
>>>>>
>>>>> My lwc.rules looks like this:
>>>>>
>>>>> 0:30:0.9
>>>>> 31:90:0.7
>>>>> 91:252:0.5
>>>>>
>>>>> so, r.category does not seem to read my range, but in stead gives me
>>>>> labels for value 31 (label=90:0.7) and value 91 (label=252:0.5)
>>>>>
>>>>> Any clues to what I am doing wrong ? or is r.category not working as
>>>>> intended?
>>>>
>>>>
>>>> You should use r.recode, not r.category.
>>>
>>> According to the manual, r.category should work with these rules.
>>
>> You're right. Sorry, I wrote to fast.
>>
>> Actually the manual also says concerning the example: "The format is
>> given as follows (when separator is set to colon)". So, AFAIU, you have
>> to set the separator parameter to whatever separator you use in the rules.
>>
>
> Sorry, I really should take the time before I write. I can reproduce the
> issue actually:
>
>
> g.copy raster=geology_30m,mygeol
> r.category mygeol rules=- separator=':' <<EOF
> 217:270:1
> 405:862:2
> 910:948:3
> EOF
> r.category mygeol
> 217	270:1
> 262	
> 270	
> 405	862:2
> 583	
> 720	
> 766	
> 862	
> 910	948:3
> 921	
> 945	
> 946	
> 948
>
> So, yes, there seems to be a bug in r.category. Please file a ticket.

Looking at the code, I actually think that r.category works well in 
terms of setting the label for the range. At least the cats file reads:

# 948 categories


0.00 0.00 0.00 0.00
217:270:1
405:862:2
910:948:3

which looks correct to me.

However, it does not know how to display it in a decent manner. The same 
goes for d.legend. Or r.what. IIUC, modules that read cat values just 
don't seem to have been foreseen for this case.

So, for the OP, I would go back to my original answer to suggest using 
r.recode.

And maybe someone who understands the code better than me can clarify 
how GRASS is supposed to actually use such range labels ?

Moritz