[Numpy-discussion] What type should / return in python 3k when applied to two integer types?

josef.pktd@gmai... josef.pktd@gmai...
Fri Aug 28 09:54:25 CDT 2009


On Fri, Aug 28, 2009 at 10:46 AM, Neal Becker<ndbecker2@gmail.com> wrote:
> Charles R Harris wrote:
>
>> On Fri, Aug 28, 2009 at 8:08 AM, <josef.pktd@gmail.com> wrote:
>>
>>> On Fri, Aug 28, 2009 at 9:55 AM, Pauli Virtanen<pav@iki.fi> wrote:
>>> > Fri, 28 Aug 2009 09:46:39 -0400, Neal Becker kirjoitti:
>>> >
>>> >> Robert Kern wrote:
>>> >>
>>> >>> On Thu, Aug 27, 2009 at 14:22, Christopher
>>> >>> Barker<Chris.Barker@noaa.gov> wrote:
>>> >>>
>>> >>>> By the way -- is there something about py3k that changes all this?
>>> >>>> Or is this just an opportunity to perhaps make some
>>> >>>> backward-incompatible changes to numpy?
>>> >>>
>>> >>> Python 3 makes the promised change of int/int => float.
>>> >>
>>> >> Does that mean that we want numpy to do the same?  I'm not so sure.
>>> >> Sounds like opening a can of worms (numpy has more types to worry
>>> >> about
>>> >> than just int and float.  If we start playing strange games we may
>>> >> regret it.)
>>> >
>>> > I believe we want to. This is not really a strange trick: it's just
>>> > that in Python 3, the operator / is true_division, and // is
>>> > floor_division. I believe any worms released by this are mostly small
>>> > and tasty...
>>> >
>>> > The main issue is probably just choosing an appropriate float return
>>> > type, and personally I believe this should be same as numpy's default
>>> > float.
>>>
>>> and getting the infs and nans as in true float division not as in
>>> np.true_divide
>>>
>>
>> Umm, good point.
>>
>> Chuck
>
> explicit is better than implicit.  IMO, if I want int/int-> float, I should
> ask for it explicitly, by casting the ints to float first (in numpy, that
> would be using astype).

if "/" has a completely different meaning in numpy than in python, it
will be a lot of work keeping track of whether you are working with
numpy ints or python ints,   a/b = ?

Josef

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