[Numpy-discussion] summing an array
Bob Dowling
rjd4+numpy at cam.ac.uk
Fri Aug 19 12:14:15 EDT 2011
On 19/08/11 15:49, Chris Withers wrote:
> On 18/08/2011 07:58, Bob Dowling wrote:
>>
>> >>> numpy.add.accumulate(a)
>> array([ 0, 1, 3, 6, 10])
>>
>> >>> numpy.add.accumulate(a, out=a)
>> array([ 0, 1, 3, 6, 10])
>
> What's the difference between numpy.cumsum and numpy.add.accumulate?
I think they're equivalent, with numpy.cumprod() serving for
numpy.multiply.accumulate()
I have a prefeence for general procedures rather than special short
cuts. The numpy.<ufunc>.accumulate works for any of the binary ufuncs I
think. The cumsum() and cumprod() functions only exist for add and
multiply.
e.g.
>>> a = numpy.arange(2,5)
>>> a
array([2, 3, 4])
>>> numpy.power.accumulate(a)
array([ 2, 8, 4096])
> Where can I find the reference docs for these?
help(numpy.ufunc)
help(numpy.ufunc.accumulate)
is where I started.
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