Hi,
thanks to both for your words! Please find comments below.
On 05/12/2011 10:01, Simone Tripodi wrote:
Hi Claudio,
what a pleasant surprise! :) I was hoping commons-graph would have
caught the interest of researchers on that field, I'm really happy you
would like to contribute!
I agree with your observations, please fill new issues on JIRA[1] and
feel free to provide patches, I'll process them ASAP :)
Alright, I'll find time later this week.
As for my suggestion on types, should I go for {{Weighted<N extends
Number>}}?
Note that I am also concerned about domain-specific requirements (e.g.
all weights must be positive) that I would like to see implemented as
"statically" as possible in the code. {{Number}} should give us quite
enough freedom in that direction (e.g. one could later extend it with
something like {{PositiveInteger}}).
A more platonic alternative would be to have an abstract type of weight
which 1. is comparable and 2. can be aggregated in some way (e.g. the
weight of a path is the sum of weights of its edges). But I am probably
going too far...
Moreover, I start having the feeling the {{WeightedGraph}} is a
useless interface: it is enough marking the vertices/edges as weighted
depending on the problem... or not? At the end of the day,
{{WeightedGraph}} does nothing than having the the edges marked as
weighted, so Dijkstra signature changed as:
<V extends Vertex, WE extends WeightedEdge, G extends DirectedGraph<V,
WE>> WeightedPath<V, WE> findShortestPath( G graph, V source, V
target )
still define well the input type, a graph wich relations are directed
edges and edges are weighted... WDYT?
I agree, as long as there are no specific features of the graph that are
independent on its vertices and edges. Another advantage: I won't bother
later to add more speficic interfaces like {{EdgeWeightedGraph}} or
{{VertexWeightedGraph}} ;-)
Ciao,
Claudio
Looking forward for your contributions, can't wait for them! :)
Simo
[1] https://issues.apache.org/jira/browse/SANDBOX
http://people.apache.org/~simonetripodi/
http://simonetripodi.livejournal.com/
http://twitter.com/simonetripodi
http://www.99soft.org/
On Mon, Dec 5, 2011 at 2:00 AM, James Carman<ja...@carmanconsulting.com> wrote:
Welcome! Contributions (and the contributor) are always welcome. In my
past life, I did quite a bit of graph programming to solve "business"
problems. We used yfiles, though. I hope to get around to playing with
[graph] someday too. Please do submit a patch!
On Dec 4, 2011 6:43 PM, "Claudio Squarcella"<squar...@dia.uniroma3.it>
wrote:
Hello,
I have been reading the source in the past days and I found that the
concept of "weight" (e.g. weighted edge, graph, etc) could benefit from a
bit of abstraction.
The basic idea would be to have an interface called Weighted with an
obvious method getWeight(). Changes in the code would easily derive from
that. As a side effect it would be easy to implement new stuff like
weighted vertices: not as glorious as weighted edges, but still needed in
some problems (e.g. all-pairs bottleneck paths) and therefore desirable for
a general purpose graph API.
One step further. A weight is not necessarily a double: in some cases not
even a number, but rather a "comparable" of some sort. So I would suggest
to make use of generics in some way, possibly the smartest. Suggestions are
welcome :-)
If my thoughts meet some interest I will work on a patch.
Ciao,
Claudio
P.S.
I am a first-timer here, so what follows is a short introduction.
I am doing a PhD in Graph Drawing and Information Visualization. I always
looked for a standard, unified way to represent and handle graphs when
developing prototypes. So my interest in this project is quite natural, and
I am willing to help and see it become a robust project.
--
Claudio Squarcella
PhD student at Roma Tre University
E-mail address: squar...@dia.uniroma3.it
Phone: +39-06-57333215
Fax: +39-06-57333612
http://www.dia.uniroma3.it/~**squarcel<http://www.dia.uniroma3.it/~squarcel>
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E-mail address: squar...@dia.uniroma3.it
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