[GRASS5] d.vect.area

[Glynn Clements]

M Lennert wrote:

> I was just wondering, Eric, why you decided to implement 
> d.vect.area with a cat-rgb file option, and not with the catnum 
> option that was in d.area. This means that for scripts like the 
> d.area.class I posted last week, I will have to go through a 
> temporary file which will hamper perfomance again... I guess all 
> this will not be a problem with the new vector format, but for the 
> time being, I liked the catnum option.

d.area's "catnum=" option just takes a list of categories, not
category/colour pairs.

Also, there's a limit on the maximum length of a command line (or,
more usually, of the combined size of the command line and the
environment list). Passing the colours via the command line would
limit the maximum number of categories which could be coloured.

Ideally, vector layers should probably have associated colour tables,
as is the case for raster layers.

As for efficiency, a version of d.area.class based upon d.vect.area
would only need to create the legend file and call d.vect.area once,
rather than having to call d.area once per colour.

-- 
Glynn Clements <glynn.clements at virgin.net>