Python Format Percentages

I use the following snippet for converting a ratio into a percentage: '{:2.1f}%'.format(value * 100) This works as you would expect. I want to extend this to be more informative in

Solution 1:

I'd recommend running round to figure out if the string formatting is going to round the ratio to 0 or 1. This function also has the option to choose how many decimal places to round to:

def get_rounded(value, decimal=1):
    percent=value*100
    almost_one = (round(percent, decimal) ==100) andpercent<100
    almost_zero = (round(percent, decimal) ==0) andpercent>0
    if almost_one:
        return "< 100.0%"
    elif almost_zero:
        return "> 0.0%"
    else:
        return "{:2.{decimal}f}%".format(percent, decimal=decimal)

for val in [0, 0.0001, 0.001, 0.5, 0.999, 0.9999, 1]:
    print(get_rounded(val, 1))

Which outputs:

0.0%
> 0.0%
0.1%
50.0%
99.9%
< 100.0%
100.0%

I don't believe there is a shorter way to do it. I also wouldn't recommend using math.isclose, as you'd have to use abs_tol and it wouldn't be as readable.

Solution 2:

Assuming Python 3.6+, marking exactly zero or exactly 100% could be done with:

>>> for value in (0.0,0.0001,.9999,1.0):
... f"{value:6.1%}{'*'if value == 0.0or value == 1.0else' '}"
...
'  0.0%*''  0.0% ''100.0% ''100.0%*'