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

[Robert Kern]

On Tue, Jan 19, 2016 at 5:36 PM, 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)`.

There are special cases that *can* be implemented and are worth doing so as
they are building blocks for other distributions that do need to avoid 0 or
1 as you say. Full-featured RNG suites do offer these:

  [0, 1]
  [0, 1)
  (0, 1]
  (0, 1)

--
Robert Kern
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