[Numpy-discussion] finding close together points.
Christopher Barker
Chris.Barker at noaa.gov
Tue Nov 10 20:17:50 EST 2009
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
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Christopher Barker, Ph.D.
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