[Numpy-discussion] tighten up ufunc casting rule
josef.pktd@gmai...
josef.pktd@gmai...
Sun Jun 5 19:06:48 CDT 2011
On Sun, Jun 5, 2011 at 6:51 PM, Gael Varoquaux
<gael.varoquaux@normalesup.org> wrote:
> On Sun, Jun 05, 2011 at 04:41:26PM -0600, Charles R Harris wrote:
>> Now, with regards to the actual failures induced by the new
>> branch, it took me a while to understand why they where happening,
>> and now I realise that we probably should have explicit coercions
>> at these locations.
>
>> So the failures in those cases is a good thing?
>
> Yes.
I remember in stats distributions, there were casting bugs like this
and they are nasty to find.
assigning a nan to an int has been changed to raise an exception, but
inline operation still produces silent results
>>> a = np.arange(3, dtype=np.int32)
>>> a[0] = np.nan
Traceback (most recent call last):
File "<pyshell#9>", line 1, in <module>
a[0] = np.nan
ValueError: cannot convert float NaN to integer
>>> a += np.nan
>>> a
array([-2147483648, -2147483648, -2147483648])
>>> a = np.arange(3, dtype=np.int32)
>>> a *= np.array([1.,1., np.nan])
>>> a
array([ 0, 1, -2147483648])
definitely wrong
Josef
>
> Gael
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