Perry Greenfield <perry@stsci.edu>: [snip]
First of all, it may make sense, but I should say a few words about what scale sizes make sense. [snip] So if you are working with much smaller arrays than 10K, you won't see total execution time decrease much
In relation to what? Using dictionaries etc? Using the array module? [snip]
Before I go further, I need to find out if the preceeding has made you gasp in horror or if the timescale is too slow for you to accept.
Hm. If you need 10000 elements before numarray pays off, I'm starting to wonder if I can use it for anything at all. :I
(This particular issue also makes me wonder if numarray would ever be a suitable substitute for the existing array module).
Indeed.
What size graphs are you most concerned about as far as speed goes?
I'm not sure. A wide range, I should imagine. But with only 100 nodes, I'll get 10000 entries in the adjacency matrix, so perhaps it's worthwile anyway?
And -- is there any chance of getting sparse matrices in numarray?
Since talk is cheap, yes :-). But I doubt it would be in the "core" and some thought would have to be given to how best to represent them. In one sense, since the underlying storage is different than numarray assumes for all its arrays, sparse arrays don't really share the same underlying C machinery very well. While it certainly would be possible to devise a class with the same interface as numarray objects, the implementation may have to be completely different.
Yes, I realise that.
On the other hand, since numarray has much better support for index arrays, i.e., an array of indices that may be used to index another array of values, index array(s), value array pair may itself serve as a storage model for sparse arrays.
That's an interesting idea, although I don't quite see how it would help in the case of adjacency matrices. (You'd still need at least one n**2 size matrix for n nodes, wouldn't you -- i.e. the index array... Right?)
One still needs to implement ufuncs and other functions (including simple things like indexing) using different machinery. It is something that would be nice to have, but I can't say when we would get around to it and don't want to raise hopes about how quickly it would appear.
No - no problem. Basically, I'm looking for a platform to implement graph algorithms that doesn't necessitate too many installed packages etc. numarray seemed promising since it's a candidate for inclusion in the standard library. I guess I'll just have to do some timing experiments...
Perry
-- Magnus Lie Hetland The Anygui Project http://hetland.org http://anygui.org