[Numpy-discussion] Behavior of np.random.uniform

[josef.pktd at gmail.com]

On Tue, Jan 19, 2016 at 12:43 PM, Charles R Harris <
charlesr.harris at gmail.com> wrote:

>
>
> On Tue, Jan 19, 2016 at 10:42 AM, Robert Kern <robert.kern at gmail.com>
> wrote:
>
>> On Tue, Jan 19, 2016 at 5:40 PM, Charles R Harris <
>> charlesr.harris at gmail.com> wrote:
>> >
>> > On Tue, Jan 19, 2016 at 10:36 AM, Robert Kern <robert.kern at gmail.com>
>> wrote:
>> >>
>> >> On Tue, Jan 19, 2016 at 5:27 PM, Charles R Harris <
>> charlesr.harris at gmail.com> wrote:
>> >> >
>> >>
>> >> > On Tue, Jan 19, 2016 at 9:23 AM, Chris Barker - NOAA Federal <
>> chris.barker at noaa.gov> wrote:
>> >> >>
>> >> >> What does the standard lib do for rand range? I see that randint Is
>> closed on both ends, so order doesn't matter, though if it raises for b<a,
>> then that's a precedent we could follow.
>> >> >
>> >> > randint is not closed on the high end. The now deprecated
>> random_integers is the function that does that.
>> >> >
>> >> > For floats, it's good to have various interval options. For
>> instance, in generating numbers that will be inverted or have their log
>> taken it is good to avoid zero. However, the names 'low' and 'high' are
>> misleading...
>> >>
>> >> They are correctly leading the users to the manner in which the author
>> intended the function to be used. The *implementation* is misleading by
>> allowing users to do things contrary to the documented intent. ;-)
>> >>
>> >> With floating point and general intervals, there is not really a good
>> way to guarantee that the generated results avoid the "open" end of the
>> specified interval or even stay *within* that interval. This function is
>> definitely not intended to be used as `uniform(closed_end, open_end)`.
>> >
>> > Well, it is possible to make that happen if one is careful or directly
>> sets the bits in ieee types...
>>
>> For the unit interval, certainly. For general bounds, I am not so sure.
>>
>
> Point taken.
>

What's the practical importance of this. The boundary points have
probability zero, theoretically.

What happens if low and high are only a few nulps apart?

If you clip the distribution to obey boundary rules you create mass points
:)

Josef


>
> Chuck
>
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