[Numpy-discussion] Graph class

David Grant davidgrant at gmail.com
Tue Aug 1 17:20:00 CDT 2006


I saw that one as well. Looks neat! Too bad they rarely mention the word
"graph" so they never come up on my google searches. I found them through
del.icio.us by searching for python and graph.

Dave

On 8/1/06, Pau Gargallo <pau.gargallo at gmail.com> wrote:
>
> you may be interested in this python graph library
> https://networkx.lanl.gov/
>
> pau
>
> On 8/1/06, David Grant <davidgrant at gmail.com> wrote:
> > I actually just looked into the boost graph library and hit a wall. I
> > basically had trouble running bjam on it. It complained about a missing
> > build file or something like that.
> >
> > Anyways, for now I can live with non-sparse implementation. This is
> mostly
> > prototyping code for integeration in to a largely Java system (with some
> > things written in C). So this will be ported to Java or C eventually.
> > Whether or not I will need to protoype something that scales to
> thousands of
> > nodes remains to be seen.
> >
> > Dave
> >
> >
> > On 8/1/06, Charles R Harris <charlesr.harris at gmail.com> wrote:
> > >
> > > Hi David,
> > >
> > > I often have several thousand nodes in a graph, sometimes clustered
> into
> > connected components. I suspect that using an adjacency matrix is an
> > inefficient representation for graphs of that size while for smaller
> graphs
> > the overhead of more complicated structures wouldn't be noticeable. Have
> you
> > looked at the boost graph library? I don't like all their stuff but it
> is a
> > good start with lots of code and a suitable license.
> > >
> > > Chuck
> > >
> > >
> > >
> > > On 8/1/06, David Grant < davidgrant at gmail.com> wrote:
> > >
> > > >
> > >
> > >
> > > I have written my own graph class, it doesn't really do much, just has
> a
> > few methods, it might do more later. Up until now it has just had one
> piece
> > of data, an adjacency matrix, so it looks something like this:
> > >
> > > class Graph:
> > >     def __init__(self, Adj):
> > >         self.Adj = Adj
> > >
> > > I had the idea of changing Graph to inherit numpy.ndarray instead, so
> then
> > I can just access itself directly rather than having to type self.Adj.
> Is
> > this the right way to go about it? To inherit from numpy.ndarray?
> > >
> > > The reason I'm using a numpy array to store the graph by the way is
> the
> > following:
> > > -Memory is not a concern (yet) so I don't need to use a sparse
> structure
> > like a sparse array or a dictionary
> > > -I run a lot of sums on it, argmin, blanking out of certain rows and
> > columns using fancy indexing, grabbing subgraphs using vector indexing
> > >
> > >
> > > --
> > > David Grant
> > > http://www.davidgrant.ca
> > >
> > >
> >
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> > --
> > David Grant
> > http://www.davidgrant.ca
> >
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-- 
David Grant
http://www.davidgrant.ca
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