[Numpy-discussion] How to get rid of the loop?
Stas K
stanconn@gmail....
Sat Nov 7 13:16:51 CST 2009
Thank you, Josef
It is exactly what I want:
>>>> ar[:,None]**2 + ar**2
Do you know something about performance of this? In my real program
ar have ~ 10k elements, and expression for v more complicated (it has
some trigonometric functions)
On 07.11.2009, at 21:57, josef.pktd@gmail.com wrote:
> On Sat, Nov 7, 2009 at 1:51 PM, Stas K <stanconn@gmail.com> wrote:
>> Can I get rid of the loop in this example? And what is the fastest
>> way
>> to get v in the example?
>>
>> ar = array([1,2,3])
>> for a in ar:
>> for b in ar:
>> v = a**2+b**2
>
>>>> ar[:,None]**2 + ar**2
> array([[ 2, 5, 10],
> [ 5, 8, 13],
> [10, 13, 18]])
>
> I think, for this case there is also directly a function in numpy
> hypot which should also work.
>
> Josef
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