RE: [jgrapht-developers] dumping adjacency and laplacian matrices

[gu b. <bou...@ya...>]

  Hi,

  Such a work is a very good news.

You mentioned that matrix representations could in
turn be
analysed and manipulated by external matrix software.

Matrix Toolkits for Java (MTJ)
http://rs.cipr.uib.no/mtj/ seems to be a candidate to
be used to complement JGraphT.

In this project a text file format is already used :
it's the matrix Market text file formats 
http://math.nist.gov/MatrixMarket/formats.html#MMformat.

I think it would be a good idea to read/write matrices
in the same format.

  
  Guillaume

--- Charles Fry <cf...@us...> a écrit :

> Hi,
> 
> Last week John invited me to join you, implementing
> myself some of the
> long list of features that I recently requested.
> While I shall initially
> be unable to implement at the same speed which I
> requested these
> features, I do hope to make some contributions to
> JGraphT, which I have
> already found to be enourmously useful, and which I
> anticipate using for
> years to come.
> 
> John suggested that I announce my proposed changes
> on this mailing list
> in an effort to solicit discussion on them prior to
> my implementation
> efforts. I will thus start with the first piece of
> functionality which I
> have already implemented externally, that I would
> like to add to
> JGraphT.
> 
> Specifically, I would like to add the ability to
> dump graphs into
> matrix representaitons which could in turn be
> analysed and manipulated
> by external matrix software. You can read more about
> this idea in the
> feature request number 1377955.
> 
> Sample output for the adjacency matrix would be:
> 
> 1 2 1
> 1 3 1
> 2 1 1
> 3 1 1
> 3 4 1
> 4 3 1
> 5 5 0
> 
> Sample output for the Laplacian matrix would be:
> 
> 1 1 2
> 1 2 -1
> 1 3 -1
> 2 2 1
> 2 1 -1
> 3 3 2
> 3 1 -1
> 3 4 -1
> 4 4 1
> 4 3 -1
> 5 5 0
> 
> The Laplacian could alternatively be in normalized
> form:
> 
>    http://mathworld.wolfram.com/LaplacianMatrix.html
> 
> John already suggested placing this in
> org._3pq.jgrapht.ext. Perhaps it
> could be called MatrixExporter? Possible static
> method names would be
> dumpAdjacencyMatrix and dumpLaplacianMatrix, but I'd
> love to hear other
> ideas.
> 
> Any feedback on this proposed functionality is
> welcome.
> 
> thanks,
> Charles
> 
> -- 
> At intersections
> Look each way
> A harp sounds nice
> But it's
> Hard to play
> Burma-Shave
> http://burma-shave.org/jingles/1941/at_intersections
> 
> 
>
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