[Numpy-discussion] Why arange has no stop-point opt-in?

josef.pktd@gmai... josef.pktd@gmai...
Thu Dec 30 08:43:12 CST 2010


On Thu, Dec 30, 2010 at 9:08 AM, Friedrich Romstedt
<friedrichromstedt@gmail.com> wrote:
> 2010/12/30 Friedrich Romstedt <friedrichromstedt@gmail.com>:
>> 2010/12/30 K.-Michael Aye <kmichael.aye@gmail.com>:
>>> I'm a bit puzzled that there seems just no way to cleanly code an
>>> interval with evenly spaced numbers that includes the stop point given?
>>> linspace offers to include the stop point, but arange does not?
>>> Am I missing something? (I am aware, that I could do
>>> arange(9,15.0001,0.1) but that's what I want to avoid!)
>>
>> Use numpy.linspace(9, 15, 7 * 10 + 1).  FYI, there is also numpy.logspace().
>
> Oh sorry, I overlooked that you're aware of the linspace functionality.  Sorry.
>
> I think opting in or opting out the end point in arange() is at even
> rate, because it's in both cases the same unreliable (about including
> or not including the end point).  Because it might pick a) if opting
> in a point just 1e-14 above so not opting in as desired and b) vice
> verse if opting out, it might pick a point just 1e-14 below.  But I
> believe someone more educated about fp issues will give a more
> authoritative reply.

Since linspace exists, I don't see much point in adding the stop point
in arange. I use arange mainly for integers as numpy equivalent of
python's range. And I often need arange(n+1) which is less writing
than arange(n, include_end_point=True)

Josef

>
> Friedrich
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