[Numpy-discussion] finding close together points.

David Goldsmith d.l.goldsmith@gmail....
Tue Nov 10 19:22:52 CST 2009


Also, is it not returning distances between points and themselves?  Or am I
misinterpreting it?

DG

On Tue, Nov 10, 2009 at 5:17 PM, Christopher Barker
<Chris.Barker@noaa.gov>wrote:

> James Bergstra wrote:
> > In some cases a brute-force approach is also good.
>
> true.
>
> > If r is a matrix of shape Nx2:
> >
> > (r*r).sum(axis=1) -2 * numpy.dot(r, r.T) +
> > (r*r).sum(axis=1).reshape((r.shape[0], 1)) < thresh**2
> >
> > It's brute force, but it takes advantage of fast matrix multiplication.
>
> I'm more concerned about memory -- doesn't this use N^2 memory? Which
> could be an issue here.
>
> -Chris
>
>
> --
> Christopher Barker, Ph.D.
> Oceanographer
>
> Emergency Response Division
> NOAA/NOS/OR&R            (206) 526-6959   voice
> 7600 Sand Point Way NE   (206) 526-6329   fax
> Seattle, WA  98115       (206) 526-6317   main reception
>
> Chris.Barker@noaa.gov
> _______________________________________________
> NumPy-Discussion mailing list
> NumPy-Discussion@scipy.org
> http://mail.scipy.org/mailman/listinfo/numpy-discussion
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.scipy.org/pipermail/numpy-discussion/attachments/20091110/85dd9db0/attachment.html 


More information about the NumPy-Discussion mailing list