Se si vuole arrotondare sempre (invece di arrotondamento alla precisione più vicino), poi farlo, in modo esplicito, con la math.floor()
function:
from math import floor
def floored_percentage(val, digits):
val *= 10 ** (digits + 2)
return '{1:.{0}f}%'.format(digits, floor(val)/10 ** digits)
print floored_percentage(0.995, 1)
Demo:
>>> from math import floor
>>> def floored_percentage(val, digits):
... val *= 10 ** (digits + 2)
... return '{1:.{0}f}%'.format(digits, floor(val)/10 ** digits)
...
>>> floored_percentage(0.995, 1)
'99.5%'
>>> floored_percentage(0.995, 2)
'99.50%'
>>> floored_percentage(0.99987, 2)
'99.98%'
fonte
2013-07-12 08:44:07