Python format size application (converting B to KB, MB, GB, TB)

Question

I am trying to write an application to convert bytes to kb to mb to gb to tb. Here\'s what I have so far:

def size_format(b):
    if b < 1000:
              r         


        

Answer 1

Yet another humanbytes version, with no loops/if..else, in python3 syntax.

Test numbers stolen from @whereisalext's answer.

Mind you, it's still a sketch, e.g. if the numbers are large enough it will traceback.

import math as m


MULTIPLES = ["B", "k{}B", "M{}B", "G{}B", "T{}B", "P{}B", "E{}B", "Z{}B", "Y{}B"]


def humanbytes(i, binary=False, precision=2):
    base = 1024 if binary else 1000
    multiple = m.trunc(m.log2(i) / m.log2(base))
    value = i / m.pow(base, multiple)
    suffix = MULTIPLES[multiple].format("i" if binary else "")
    return f"{value:.{precision}f} {suffix}"


if __name__ == "__main__":
    sizes = [
        1, 1024, 500000, 1048576, 50000000, 1073741824, 5000000000,
        1099511627776, 5000000000000]

    for i in sizes:
        print(f"{i} == {humanbytes(i)}, {humanbytes(i, binary=True)}")

Results:

1 == 1.00 B, 1.00 B
1024 == 1.02 kB, 1.00 kiB
500000 == 500.00 kB, 488.28 kiB
1048576 == 1.05 MB, 1.00 MiB
50000000 == 50.00 MB, 47.68 MiB
1073741824 == 1.07 GB, 1.00 GiB
5000000000 == 5.00 GB, 4.66 GiB
1099511627776 == 1.10 TB, 1.00 TiB
5000000000000 == 5.00 TB, 4.55 TiB

Update:

As pointed out in comments (and as noted originally: "Mind you, it's still a sketch"), this code is slow and buggy. Please see @mitch-mcmabers 's answer.

Update 2: I was also lying about having no ifs.