[Numpy-discussion] summing an array

Bob Dowling rjd4+numpy@cam.ac...
Thu Aug 18 09:58:25 CDT 2011


On 18/08/11 15:19, Chris Withers wrote:

> Hopefully a simple newbie question, if I have an array such as :
>
> array([0, 1, 2, 3, 4])
>
> ...what's the best way to cummulatively sum it so that I end up with:
>
> array([0, 1, 3, 6, 10])
>
> How would I do this both in-place and to create a new array?

 >>> a = numpy.arange(0,5)

 >>> a
array([0, 1, 2, 3, 4])

 >>> numpy.add.accumulate(a)
array([ 0,  1,  3,  6, 10])

 >>> numpy.add.accumulate(a, out=a)
array([ 0,  1,  3,  6, 10])

 >>> a
array([ 0,  1,  3,  6, 10])

 >>>


And similarly with numpy.multiply for products etc.


More information about the NumPy-Discussion mailing list