[Numpy-discussion] Really strange result

Charles R Harris charlesr.harris@gmail....
Fri May 1 20:39:32 CDT 2009


On Fri, May 1, 2009 at 7:24 PM, Neal Becker <ndbecker2@gmail.com> wrote:

> Charles R Harris wrote:
>
> > On Fri, May 1, 2009 at 1:02 PM, Neal Becker <ndbecker2@gmail.com> wrote:
> >
> >> In [16]: (np.linspace (0, len (x)-1, len(x)).astype (np.uint64)*2).dtype
> >> Out[16]: dtype('uint64')
> >>
> >> In [17]: (np.linspace (0, len (x)-1, len(x)).astype (np.uint64)*n).dtype
> >> Out[17]: dtype('float64')
> >>
> >> In [18]: type(n)
> >> Out[18]: <type 'int'>
> >>
> >> Now that's just strange.  What's going on?
> >>
> >>
> > The  n is signed, uint64 is unsigned. So a signed type that can hold
> > uint64 is needed. There ain't no such integer, so float64 is used. I
> think
> > the logic here is a bit goofy myself since float64 doesn't have the
> needed
> > 64 bit precision and the conversion from int kind to float kind is
> > confusing. I think it would be better to raise a NotAvailable error or
> > some such. Lest you think this is an isolated oddity, sometimes numeric
> > arrays can be converted to object arrays.
> >
> > Chuck
>
> I don't think that any type of integer arithmetic should ever be
> automatically promoted to float.
>
> Besides that, what about the first example?  There, I used '2' rather than
> 'n'.  Is not '2' also an int?


What version of numpy are you using?

Chuck
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