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

Christopher Barker Chris.Barker@noaa....
Thu Aug 27 16:22:39 CDT 2009


Robert Kern wrote:
> On Thu, Aug 27, 2009 at 12:43, Charles R
> Harris<charlesr.harris@gmail.com> wrote:
>> In [3]: floor_divide(x,y).dtype
>> Out[3]: dtype('float64')
> 
> Ewww. It should be an appropriate integer type. Probably whatever x*y is.

+1 if you are working with integers, you should get integers, because 
that's probably what you want. -- they can overflow, etc. anyway, so 
buyer beware!

In [7]: x.dtype
Out[7]: dtype('int64')

In [8]: y.dtype
Out[8]: dtype('uint64')

In [9]: (x * y).dtype
Out[9]: dtype('float64')

hmmm -- I thought we had removed this kind of silent upcasting 
(particularly int-> float), but I guess when you mix two types, numpy 
has to choose something!

In any case, x/y should probably return the same type as x*y.

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?

-Chris







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Christopher Barker, Ph.D.
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