[Numpy-discussion] Really strange result

Charles R Harris charlesr.harris at gmail.com
Fri May 1 18:58:42 EDT 2009


On Fri, May 1, 2009 at 1:02 PM, Neal Becker <ndbecker2 at 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
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