[Numpy-discussion] formatting issues, locale and co

Charles R Harris charlesr.harris@gmail....
Mon Dec 29 01:36:29 CST 2008


On Sun, Dec 28, 2008 at 10:35 PM, David Cournapeau <
david@ar.media.kyoto-u.ac.jp> wrote:

> Charles R Harris wrote:
> >
> >
> >
> >     I put my yesterday work in the fix_float_format branch:
> >      - it fixes the locale issue
> >      - it fixes the long double issue on windows.
> >      - it also fixes some tests (we were not testing single precision
> >     formatting but twice double precision instead - the single precision
> >     test fails on the trunk BTW).
> >
> >
> > Curious, I don't see any test failures here. Were the tests actually
> > being run or is something else different in your test setup? Or do you
> > mean the fixed up test fails.
>
> The later: if you look at numpy/core/tests/test_print, you will see that
> the types tested are np.float, np.double and np.longdouble, but at least
> on linux, np.float == np.double, and np.float32 is what we want to test
> I suppose here instead.
>
> >
> > Expected, but I would like to see it change because it is kind of
> > frustrating. Fixing it probably involves setting a function pointer in
> > the type definition but I am not sure about that.
>
> Hm, it took me a while to get this, but print np.float32(value) can be
> controlled through tp_print. Still, it does not work in all cases:
>
> print np.float32(a) -> call the tp_print
> print '%f' % np.float32(a) -> does not call the tp_print (nor
> tp_str/tp_repr). I have no idea what going on there.
>

I'll bet it's calling a conversion to python float, i.e., double, because of
the %f.

In [1]: '%s' % np.float32(1)
Out[1]: '1.0'

In [2]: '%f' % np.float32(1)
Out[2]: '1.000000'

I don't see any way to work around that without changing the way the python
formatting works.

Chuck
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