On Thu, Feb 9, 2012 at 3:40 PM, Benjamin Root <ben.r...@ou.edu> wrote:
> > > On Thursday, February 9, 2012, Sturla Molden <stu...@molden.no> wrote: > > > > > > Den 9. feb. 2012 kl. 22:44 skrev eat <e.antero.ta...@gmail.com>: > > > >> > > Maybe this issue is raised also earlier, but wouldn't it be more > consistent to let arange operate only with integers (like Python's range) > and let linspace handle the floats as well? > > > > > > Perhaps. Another possibility would be to let arange take decimal > arguments, possibly entered as text strings. > > Sturla > > > Personally, I treat arange() to mean, "give me a sequence of values from x > to y, exclusive, with a specific step size". Nowhere in that statement > does it guarantee a particular number of elements. Whereas linspace() > means, "give me a sequence of evenly spaced numbers from x to y, optionally > inclusive, such that there are exactly N elements". They complement each > other well. > I agree -- both functions are useful and I think about them the same way. The unfortunate part is that tiny precision errors in y can make arange appear to be "sometimes-exclusive" rather than always exclusive. I've always imagined there to be a sort of duality between the two functions, where arange(low, high, step) == linspace(low, high-step, round((high-low)/step)) in cases where (high - low)/step is integral, but it turns out this is not the case. > > There are times when I intentionally will specify a range where the step > size will not nicely fit. i.e.- np.arange(1, 7, 3.5). I wouldn't want this > to change. > Nor would I. What I meant to express earlier is that I like how Matlab addresses this particular class of floating point precision errors, not that I think arange output should somehow include both endpoints. > > My vote is that if users want matlab-colon-like behavior, we could make a > new function - maybe erange() for "exact range"? > > Ben Root > That could work; it would completely replace arange for me in every circumstance I can think of, but I understand we can't just go changing the behavior of core functions. Drew
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