[Numpy-discussion] finding close together points.

[David Goldsmith]

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 at 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
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>
> Chris.Barker at noaa.gov
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