[Numpy-discussion] distance matrix speed

David Douard david.douard at logilab.fr
Fri Jun 16 02:53:37 CDT 2006


Hi,

On Fri, Jun 16, 2006 at 08:28:18AM +0200, Johannes Loehnert wrote:
> Hi,
> 
> def dtest():
>     A = random( [4,2])
>     B = random( [1000,2])
> 
>     # drawback: memory usage temporarily doubled
>     # solution see below
>     d = A[:, newaxis, :] - B[newaxis, :, :]

Unless I'm wrong, one can simplify a (very) little bit this line: 
      d = A[:, newaxis, :] - B

>     # written as 3 expressions for more clarity
>     d = sqrt((d**2).sum(axis=2))
>     return d
> 



-- 
David Douard                             LOGILAB, Paris (France)
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