[Numpy-discussion] What type should / return in python 3k when applied to two integer types?
Charles R Harris
charlesr.harris@gmail....
Fri Aug 28 11:46:17 CDT 2009
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
>
Note that currently true_divide returns zeros in these cases and attempts --
unsuccessfully -- to raise a zero division error; that is what python does.
So if we make this change there will be a divergence from python behaviour.
However, arrays are different from scalars and I think we should make this
change.
Chuck
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