Re: [Numpy-discussion] can this be made faster?

[Daniel M. <dm...@gm...>]

On 10/8/06, Greg Willden <gre...@gm...> wrote:
> On 10/8/06, Daniel Mahler <dm...@gm...> wrote:
> >
> > >>> a
> > array([0, 0])
> > >>> b
> > array([0, 1, 0, 1, 0])
> > >>> c
> > array([1, 1, 1, 1, 1])
> >
>
>
> Well for this particular example you could do
> a=array([len(b)-sum(b), sum(b)])
> Since you are just counting the ones and zeros.
>
> This next one is a little closer for the case when c is not just a bunch of
> 1's but you still have to know how the highest number in b.
> a=array([sum(c[b==0]),  sum(c[b==1]), ... sum(c[b==N]) ] )
>
> So it sort of depends on your ultimate goal.
> Greg
> Linux.  Because rebooting is for adding hardware.

In my case all a, b, c are large with b and c being orders of
magnitude lareger than a.
b is known to contain only, but potentially any, a-indexes,  reapeated
many times.
c contains arbitray floats.
essentially it is to compute class totals
as in total[class[i]] += value[i]

Daniel