[Numpy-discussion] numpy.int32 is not subclass of int, but numpy.int64 is

Olivier Delalleau shish@keba...
Tue Nov 15 06:02:30 CST 2011


2011/11/14 Robert Kern <robert.kern@gmail.com>

> On Mon, Nov 14, 2011 at 20:18, MACKEITH Andrew <Andrew.MACKEITH@3ds.com>
> wrote:
> > Could someone explain this?
> >
> > An instance of numpy.int32 is not an instance of int or numpy.int.
> > An instance of numpy.int64 is an instance of int and numpy.int.
> >
> > I don't know if it is a bug in my linux build.
>
> >>>> import sys
> >>>> sys.maxint
> > 9223372036854775807
> >>>> import platform
> >>>> print  platform.platform()
> > Linux-2.6.32.12-0.7-default-x86_64-with-SuSE-11-x86_64
>
> This is expected on a 64-bit platform. Note that numpy.int is just an
> alias for the builtin int type for backwards compatibility with an
> earlier version of numpy. We could probably remove it, since it seems
> to be causing more confusion than not.
>
> Anyways, we subclass the appropriately sized integer scalar type from
> Python's int type depending on the platform. So on a platform where
> Python's int type is 64-bits, numpy.int64 will include int in its
> inheritance tree. On platforms where the Python int type is 32-bit,
> numpy.int32 will include it instead.


I'll just add that there is a numpy.integer class that is parent of both
numpy.int32 and numpy.int64 (see
http://docs.scipy.org/doc/numpy/reference/arrays.scalars.html). It's not a
parent of numpy.int though, since as said above, numpy.int is an alias to
the builtin int.

-=- Olivier
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