humanize_bytes

from __future__ import division
import doctest


def humanize_bytes(bytes, precision=1):
    """Return a humanized string representation of a number of bytes.

    Assumes `from __future__ import division`.

    >>> humanize_bytes(1)
    '1 byte'
    >>> humanize_bytes(1024)
    '1.0 kB'
    >>> humanize_bytes(1024*123)
    '123.0 kB'
    >>> humanize_bytes(1024*12342)
    '12.1 MB'
    >>> humanize_bytes(1024*12342,2)
    '12.05 MB'
    >>> humanize_bytes(1024*1234,2)
    '1.21 MB'
    >>> humanize_bytes(1024*1234*1111,2)
    '1.31 GB'
    >>> humanize_bytes(1024*1234*1111,1)
    '1.3 GB'
    """
    abbrevs = (
        (1<<50L, 'PB'),
        (1<<40L, 'TB'),
        (1<<30L, 'GB'),
        (1<<20L, 'MB'),
        (1<<10L, 'kB'),
        (1, 'bytes')
    )
    if bytes == 1:
        return '1 byte'
    for factor, suffix in abbrevs:
        if bytes >= factor:
            break
    return '%.*f %s' % (precision, bytes / factor, suffix)


if __name__ == '__main__':
    doctest.testmod()