friendly-number.py

def friendly_number(number, base=1000, decimals=0, suffix='',
                    powers=['', 'k', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y']):
    prefix, zn = '', ''
    if number < 0:
        zn = "-"
    number, answer = abs(number), number

    for i, power in enumerate(powers):
        if number // (base**i) > 0:
            answer = number // (base**i)
            prefix = powers[i]

    if decimals:
        i = powers.index(prefix)
        frac = round(float(number) / (base**i), decimals)
        a_lst = str(frac).split(".")
        answer = a_lst[0] + "." + a_lst[1].zfill(decimals)

    return zn+str(answer)+prefix+suffix


def test_function():
    assert friendly_number(102) == '102', '102'
    assert friendly_number(10240) == '10k', '10k'
    assert friendly_number(12341234, decimals=1) == '12.3M', '12.3M'
    assert friendly_number(12461, decimals=1) == '12.5k', '12.5k'
    assert friendly_number(1024000000, base=1024, suffix='iB') == '976MiB', '976MiB'
    assert friendly_number(12000000, decimals=3) == '12.000M'
    assert friendly_number(-150, base=100, powers=['', 'd', 'D']) == '-1d'
    assert friendly_number(-155, base=100, decimals=1, powers=['', 'd', 'D']) == '-1.6d'
    assert friendly_number(255000000000, powers=['', 'k', 'M']) == '255000M'

if __name__ == '__main__':
    test_function()