[Numpy-discussion] Deprecating silent truncation of floats when assigned to int array

[Ralf Gommers]

On Tue, Jun 14, 2016 at 12:23 AM, Ian Henriksen <
insertinterestingnamehere at gmail.com> wrote:

> Personally, I think this is a great idea. +1 to more informative errors.
>

+1 from me as well

Ralf



> Best,
> Ian Henriksen
>
> On Mon, Jun 13, 2016 at 2:11 PM Nathaniel Smith <njs at pobox.com> wrote:
>
>> It was recently pointed out:
>>
>>   https://github.com/numpy/numpy/issues/7730
>>
>> that this code silently truncates floats:
>>
>> In [1]: a = np.arange(10)
>>
>> In [2]: a.dtype
>> Out[2]: dtype('int64')
>>
>> In [3]: a[3] = 1.5
>>
>> In [4]: a[3]
>> Out[4]: 1
>>
>> The proposal is that we should deprecate this, and eventually turn it
>> into an error. Any objections?
>>
>> We recently went through a similar deprecation cycle for in-place
>> operations, i.e., this used to silently truncate but now raises an
>> error:
>>
>> In [1]: a = np.arange(10)
>>
>> In [2]: a += 1.5
>>
>> ---------------------------------------------------------------------------
>> TypeError                                 Traceback (most recent call
>> last)
>> <ipython-input-2-9cf893a64492> in <module>()
>> ----> 1 a += 1.5
>>
>> TypeError: Cannot cast ufunc add output from dtype('float64') to
>> dtype('int64') with casting rule 'same_kind'
>>
>> so the proposal here is to extend this to regular assignment.
>>
>> -n
>>
>> --
>> Nathaniel J. Smith -- https://vorpus.org
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>>
>
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