[SciPy-dev] scipy.spatial 'output' args
Sat Feb 21 19:59:27 CST 2009
On Fri, Feb 20, 2009 at 1:21 AM, David Warde-Farley <email@example.com> wrote:
> This is mostly a question for Damian (sorry, I seem to be bugging you
> on a lot of fronts!). I'm wondering if there's a principled reason why
> the pdist/squareform/etc. functions don't allow you to specify an
> output array.
> It seems hard to justify not having a way of avoiding repeated memory
> allocations if you're doing this more than once (as points change, for
> example -- if you're curious I'm implementing a 2-D embedding
> algorithm and the objective function relies on a lot of distances
> being recomputed).
There is no reason why I did not provide an 'out' parameter for
preallocated memory in these functions. This is probably just a
MATLABism oversight. I'd encourage you to add this feature. If you do,
please make sure to do the following:
* the array holds the right number of values,
* its C contiguous (the C functions don't do any special striding),
* the data type of the out array is 'f',
Please provide regression tests, making sure the exception is thrown
in these appropriate cases. See 'test_distance.py' for the nose tests.
Thanks so much for agreeing to add this feature.
> My guess is this is a MATLABism and that this was just an oversight.
> Is there a reason I shouldn't go about trying to add it? Would other
> people find this useful?
> Scipy-dev mailing list
Damian Eads Ph.D. Student
Jack Baskin School of Engineering, UCSC E2-489
1156 High Street Machine Learning Lab
Santa Cruz, CA 95064 http://www.soe.ucsc.edu/~eads
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