[GRASS-dev] future thematic cartography in GRASS [was: Re: [GRASS GIS] #974: [Patch] add option to d.vect to make symbol size proportionate to square root of size_column]

[Moritz Lennert]

On 03/03/10 11:44, Hamish wrote:
>> However, if we go this way, I would need to add a flag to
>> d.vect which allows sorting symbols with the largest in the
>> back. This is absolutely necessary for readability. However,
>> this implies a fundamental change in the d.vect code,
>
> As this is just the beginning, I would prefer a new module for that
> along the lines of d.vect.chart.

Ok, I'll go in this direction then.

> why not simplify the name to just "d.thematic"?

The idea was to simplify modules and so to separate areas from symbols 
(incl. lines), but it is obviously possible to put everything together 
into one module.

> ps- see also v.colors and the new extra/ring symbol

Yeah, we could include discrete color schemes in v.colors by feeding it 
class breaks.

So in summary this means as tasks at hand:

- write an alternative d.vect with attribute-based selection, allowing 
sorting of symbols largest in the back

- enhance v.colors to provide discrete color schemes (possibly including 
the color brewer schemes which are licensed under the Apache license)

- write a script which combines the existing tools (v.class, v.colors, 
d.vect / d.vect2) to allow for thematic cartography

- write a module/script which displays thematic legends (color classes 
and sizes)

This would make d.thematic.area obsolete.

As mentioned, my time is limited and I don't know how quickly I could do 
all this. If anyone's interested in helping, this would be great.

Moritz