[GRASS-dev] Re: test of v.area.thematic

[Moritz Lennert]

On 02/01/08 19:53, Michael Barton wrote:
>> This should work:
>>
>> d.area.thematic map=censusblk_swwake data=total_pop breaks=`v.class -g
>> map=censusblk_swwake column=total_pop algo=std nbcla=4`
>> colors=0:0:255,0:0:100,100:0:0,255:0:0 layer=1 bwidth=0 bcolor=yellow
>> render=l
> 
> Thanks Moritz. I'll try this when I get to my other computer.
> 
> Why are you using backquotes here? This seems non-standard with respect 
> to other GRASS commands. Any idea if this works better (or worse) on 
> Windows and in a GUI setting?

Backquotes in *nix shell mean "the results of the command within these 
backquotes". Theoretically it also should work in windows cmd.exe (but 
will have to try to be sure)...

AFAIK, in the automatically created gui you cannot pass any information 
from one module to another and (just tried) a back quoted command does 
not work either, so the only way would be to create a file option in 
v.class to write to a file and another file option in d.area.thematic to 
read from it. Not sure if this is really worth it, though. I think that 
for those who will use a gui we need to create a special thematic 
mapping gui which combines all the modules doing something like (no idea 
of the real python commands):

breaks=os.system('v.class -g ...')
legend=os.system('d.area.thematic -l ... breaks=breaks')

In any case, it was just a quick example for early-birds like you ;-)

Moritz