[GRASS5] New thematic mapper for GRASS 6

[Moritz Lennert]

Michael,

On Wed, May 11, 2005 7:39, Michael Barton said:
> I¹ve just finished a thematic mapper for vector maps in GRASS 6,
d.vect.thematic, and am hoping that some of you can help test it.


This is way cool !

I had been thinking about something like this for a while, but as always, I
think too much and do too little ;-)

First superficial testing shows it works great, with just a few remarks:

- One problem I encounter sometimes (still trying to figure out the exact
sequence leading to this) is the following error:

/usr/local/grass-6.1.cvs/scripts/d.vect.thematic: line 143: TMP1: Permission
denied

and then nothing is displayed as the file suppoed to contain the statistics is
empty.


- The options available in the key "type" should be reduced to the only
sensible ones (point, centroid, area) as the others don't seem to work (or I
misunderstood something); also it might be useful to print a warning if the
type of thematic map display is set to "graduated points" and the vector map
type to "area" and vice versa. Currently the program runs, but nothing shows
up.


- Concerning the legend: it would be good to have a precise indication of
where one category ends and the other starts. At the moment, it prints
something like

1.000000-3.2725				5
3.2725-5.545				7
5.545-7.8175				9
7.8175-10.09				11

so if you have a value of 3.2725, you don't know in which category it is...
If I understand the code correctly it is in the first category and the legend
should therefore be:

1.000000-3.2725				5
3.2726-5.545				7


or some other way of saying that the range goes from minimum (exclusive) to
maximum (inclusive).
BTW the way, this raises the question of what happens if a feature has exactly
the $min value of the first category ?


And just to prove once again that users are a terribly ungrateful bunch and
always want more, here a few wishes:

- I think one useful addition would be the possibility to display the
available columns, or, even better, to chose from a list of available columns.

- It was very easy for me to very quickly create a new color scheme (here we
use blue for low values and red for high values...) in the script. That's very
useful for those of us who are not afraid of going into the code. But it would
be interesting to see if there is a way to offer a color choser to chose the
min and max color and to automatically calculate the intermediate values.
Another great option would be to also be able to chose all the colors
manually...

Congrats Michael, this will make GRASS much usable for all the vector bunch
out there !

Moritz