[Numpy-discussion] FutureWarning: comparison to `None` will result in an elementwise object comparison in the future.

[Andreas Hilboll]

On 08.04.2015 20:30, Nathaniel Smith wrote:
> On Apr 8, 2015 2:16 PM, "Andreas Hilboll" <lists at hilboll.de
> <mailto:lists at hilboll.de>> wrote:
>>
>> Hi all,
>>
>> I'm commonly using function signatures like
>>
>>    def myfunc(a, b, c=None):
>>        if c is None:
>>            # do something ...
>>        ...
>>
>> where c is an optional array argument.  For some time now, I'm getting a
>>
>>    FutureWarning: comparison to `None` will result in an elementwise
>>    object comparison in the future
>>
>> from the "c is None" comparison.  I'm wondering what would be the best
>> way to do this check in a future-proof way?
> 
> As far as I know, you should be getting the warning when you write
>   c == None
> and the fix should be to write
>   c is None
> instead. (And this is definitely an important fix -- it's basically a
> bug in numpy that the == form ever worked.) Are you certain that you're
> getting warnings from 'c is None'?

My mistake; I was actually doing

    if p1 is None == h1 is None:

instead of

    if (p1 is None) == (h1 is None):

Sorry for the noise.

-- Andreas.