[GRASSLIST:2673] Re: New Interested!

[Greg Sepesi]

> 
> Hi all, Hi Radim. It's a while I'm out of this job. I'm still wondering to start
> back with development of DGLib. It's a hard work for free... I'm happy to
> see that it was somehow useful. At the user's conference in september 2002
> there was little interest and it was one of the reasons that made me give up
> developing in that direction. I know there are design limits in the library (use
> of AVLs); it is suitable for low-degree graphs, as road-networks are.
> 
> Roberto
> 

Hello!

The infamous Roberto Micarelli really exists!  I have never been to a
GRASS conference, so I don't know what the reaction was to DGLib in
2002, but there certainly seems to be a lot of people now interested in
GRASS's new vector capabilities including DGLib.  I'm not sure where
Radim gets his energy.

Last summer I spent a couple days looking at DGLib, and didn't
understand your use of AVL trees enough to attempt to use it.  In my
application, I'm more concerned with graph search speed than graph
update flexibility (which I presume was your reasoning behind using AVL
trees), so I implemented a LGPL directed graph library based upon lookup
tables.  I called it dgtable and the doxygen documentation for it is at

	http://www.eduneer.com/gad/html/index.html

In addition to the use of lookup tables, another deviation from DGLib is
that most of dgtable's directed graph algorithm results are stored in a
"directed graph state" (instead of a newly created result directed
graph) that gets attached to a directed graph.  After noticing that most
directed graph algorithms don't produce results with more vertices than
there are vertices in the graph, I just added more storage for directed
graph algorithm results to each vertex storage that was already required
by the directed graph state.  Therefore dgtable doesn't need to create
and maintain graphs for results, except for vertex generating algorithms
such as Delauney triangulation.

Aside from my investigation of DGLib, I haven't spent much time working
with GRASS because my application is more focused on geographical
documentation rather geographical analysis.  However I do think there is
an intriguing complementary relationship between the two.  I've written
about it at

	http://www.eduneer.com/gad/anvdoc.pdf

and would welcome a discussion of how geographical analysis, GRASS in
particular, and geographical documentation could benifit from and
integrate with each other.

Greg