[Numpy-discussion] product of arrays of different lengths

Francesc Alted faltet@pytables....
Mon Sep 15 08:32:15 CDT 2008


A Monday 15 September 2008, Alan G Isaac escrigué:
> On 9/15/2008 6:25 AM Francesc Alted apparently wrote:
> > max_idx = min(len(A), len(B))
> > (A[:max_idx] * B[:max_idx]).sum()
> >
> > which does not require a copy becuase the [:max_idx] operator
> > returns just a view of the arrays.
>
> But it still requires creating a new array,
> so perhaps use of ``dot`` above or even::
>
> 	sum(ai*bi for ai,bi in izip(A,B))
>
> is worth considering in this case.
> (That is the built-in ``sum``.)

Yeah.  Good point.

-- 
Francesc Alted


More information about the Numpy-discussion mailing list