[Numpy-discussion] faster code

[Keith Goodman]

On Mon, May 17, 2010 at 11:06 AM, Francesc Alted <faltet at pytables.org> wrote:
> A Sunday 16 May 2010 21:14:34 Davide Lasagna escrigué:
>> Hi all,
>>
>> What is the fastest and lowest memory consumption way to compute this?
>>
>> y = np.arange(2**24)
>> bases = y[1:] + y[:-1]
>>
>> Actually it is already quite fast, but i'm not sure whether it is occupying
>> some temporary memory
>> is the summation. Any help is appreciated.
>
> Both y[1:] and y[:-1] are views of the original y array, so you are not
> wasting temporary space here.  So, as I see this, the above idiom is as
> efficient as it can get in terms of memory usage.

I thought that this

y[:-1] += y[1:]

uses half the memory of this

bases = y[1:] + y[:-1]