Alexander Schmolck wrote:
> Robert Kern <[EMAIL PROTECTED]> writes:
>
>> Alexander Schmolck wrote:
>>> Robert Kern <[EMAIL PROTECTED]> writes:
>>>
>>>> If possible, I would prefer a way to pass a value to use and raise the
>>>> error if
>>>> no such value is passed rather than hardcode an identity value for min()
>>>> and max().
>>> What's wrong with inf? I'm not sure integer reductions should have
>>> max/min-ints as identity values (because this could lead to nasty bugs when
>>> implicit dtype promotions are involved), but I can't see any problems
>>> resulting from +/-inf.
>> 0 and 1 exist in both integer and floating point versions. +/-inf don't. A
>> hardcoded identity value should be consistent across all uses, not changing
>> depending on the type .
>
> I don't see why the integer case can't just throw an error, because I don't
> see how this could cause much trouble.
The floating point case should also throw an error if the integer case does.
> OTOH I have no difficulty thinking of
> current 'special' integer-behavior that I find quite problematic, e.g.
>
> seterr('ignore'); divide(1,0) == 0 # no error, no warning[1]
>
>> (and we shouldn't use +/-inf for integer arrays, either)
>
> Agreed.
>
>> There are also times when I have constraints on the domain of the inputs. For
>> example, I might be dealing with arrays that should only have positive
>> numbers.
>> If I call max() on the arrays, I might want the result for the empty one to
>> be
>> 0, not -inf.
>
> I don't find this argument convincing -- add.reduce won't care that your
> numbers are all positive and add.multiply won't care if they're all negative.
Correct, they won't. It also doesn't matter that they won't. It does for min()
and max(), though.
>> Besides, being able to specify what value to use to start the reduction is a
>> generally useful feature regardless.
>
> Yes, I agree that this it should be possible to pass a seed value, but that is
> to my mind largely an orthogonal issue.
It is a largely orthogonal issue; however, it also happens to solve the issue at
hand without introducing other weirdness.
--
Robert Kern
"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco
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