humanize_bytes.py

def humanize_bytes(nbytes, output_format='%.2f %s%s', suffix=None):
    if suffix is None:
        suffix = 'iB'
    basis = 1024.0 if suffix == 'iB' else 1000.0

    for unit in ['', 'K', 'M', 'G', 'T', 'P', 'E', 'Z']:
        if abs(nbytes) < basis:
            return output_format % (nbytes, unit, suffix)
        nbytes /= basis
    return output_format % (nbytes, 'Y', suffix)

numbers = [10430, 11000000000, 343100000]
assert [humanize_bytes(n) for n in numbers] == ['10.2KiB', '10.2GiB', '327.2MiB']
assert [humanize_bytes(n, suffix='B') for n in numbers] == ['10.4KB', '11.0GB', '343.1MB']