On 23 March 2015 at 12:52, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: > I have a numeric value, possibly a float, Decimal or (improper) Fraction, > and I want the fractional part. E.g. fract(2.5) should give 0.5. > > Here are two ways to do it: > > py> x = 2.5 > py> x % 1 > 0.5 > py> x - int(x) > 0.5 > > x % 1 is significantly faster, but has the disadvantage of giving the > complement of the fraction if x is negative: > > py> x = -2.75 > py> x % 1 > 0.25
The other version gives -0.75 in this case so I guess that's what you want. > Are there any other, possibly better, ways to calculate the fractional part > of a number? What do you mean by better? Is it just faster? To modify the % version so that it's equivalent you can do: >>> x = -2.75 >>> (x % 1) - (x < 0) -0.75 I'm not sure if that's faster than x - int(x) though. Obviously it depends which numeric type you're primarily interested in. Oscar -- https://mail.python.org/mailman/listinfo/python-list
