Subject: [Thuban-list] first stabs at a "visual" classifier

From: "Daniel Calvelo" <[email-masked]>
Date: Fri, 11 Jul 2003 16:28:10 -0500

Hi.

In the attachment you will find a set of files and a patch against what was
the June 20th CVS. They provide the beginnings of a custom classifier. Let me
elaborate.

The patch adds a "Custom breaks" option to the class generator. When selected,
it opens a graphical display of the selected field that includes: a histogram
(a slider controls the number of bins used), a "pointgram" (a point, or rather
a vertical bar for each data value) and a set of triangular markers indicating
breaks. These markers can be deleted (double-click) and added (single-click on
a new location). They represent cut points from which a set of ranges will be
generated.

It's visually awful, and lacks useful tricks like value display, a grid-like
positioning method and true sliding capabilities for the markers, but it gives
good visual clues  for manual classification of field values.

Let me know if it's worth enhancing. In coding it, I found several ways in
which it might become a permanent display for the other classifiers, as a
visual guide, but that would require severe tweaking with the classification
infrastructure.

Cheers,

Daniel.

-- Daniel Calvelo Aros
-- Dirección General de Información Agraria
-- Ministerio de Agricultura del Perú
-- (51-1) 424-9001

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From: Jan-Oliver Wagner <[email-masked]>
Date: Mon, 21 Jul 2003 17:45:47 +0200

Hi Daniel,

> visual guide, but that would require severe tweaking with the classification

thanks for sending this piece of code. It looks promising (there are
currently some flaws in it).
We would like to incorporate it into Thuban, but don't have the time
to stabilize this feature on our own for 1.0.

If your time permits, it would be great if you could work on
this feature. We would incorporate it into the CVS for this purpose.
Then you can produce diff's against the CVS version which would
make it easier for us to incorporate updates. (BTW: diff -u or
diff -c would be nicer than just a diff).

Furthermore, for adding your contribution to Thuban, we need
your expression of intend of transferring the copyright to
us or to the Free Software Foundation Europe (FSFE) or to other
organization dedicated to Free (GIS) Software via the
Fiduciary License Agreement (FLA). If you send
this expression of intend with a GnuPG-signed E-Mail
it should be OK for now. A FLA can be done later.

We ask for this procedure for any major contribution
to ensure legal maintainebility of the codebase.

We plan to transfer Thuban via FLA to Free Software Foundation
Europe anyway :-)
It might take a couple of month though.

Best

	Jan
-- 
Jan-Oliver Wagner               http://intevation.de/~jan/

Intevation GmbH	              	     http://intevation.de/
FreeGIS	                               http://freegis.org/