Some prettification functions.

prettify.py

#!/usr/bin/python

"""
Some prettification functions.

    >>> humanize(1024, is_bytes=True)
    '1.0 kB'
    >>> humanize(1000*12342)
    '12.3 M'
    >>> pretty_num(1255000)
    '1,255,000'

"""

import locale

def humanize(d, precision=1, is_bytes=False):
    """Return a humanized string representation of a number.

    >>> humanize(1, is_bytes=True)
    '1 byte'
    >>> humanize(1024, is_bytes=True)
    '1.0 kB'
    >>> humanize(1024*123, is_bytes=True)
    '123.0 kB'
    >>> humanize(1024*12342, is_bytes=True)
    '12.1 MB'
    >>> humanize(1024*12342, precision=2, is_bytes=True)
    '12.05 MB'
    >>> humanize(1024*1234, precision=2, is_bytes=True)
    '1.21 MB'
    >>> humanize(1024*1234*1111, precision=2, is_bytes=True)
    '1.31 GB'
    >>> humanize(1024*1234*1111, precision=1, is_bytes=True)
    '1.3 GB'
    >>> humanize(1)
    '1'
    >>> humanize(1000)
    '1.0 k'
    >>> humanize(1000*123)
    '123.0 k'
    >>> humanize(1000*12342)
    '12.3 M'
    >>> humanize(1000*12342, precision=2)
    '12.34 M'
    >>> humanize(1000*1234, precision=2)
    '1.23 M'
    >>> humanize(1000*1234*1111, precision=2)
    '1.37 G'
    >>> humanize(1000*1234*1111, precision=1)
    '1.4 G'
    """
    abbrevs_bytes = (
        (1<<50L, 'PB'),
        (1<<40L, 'TB'),
        (1<<30L, 'GB'),
        (1<<20L, 'MB'),
        (1<<10L, 'kB'),
        (1, 'bytes')
    )

    abbrevs_si = (
        (1e15, 'P'),
        (1e12, 'T'),
        (1e9,  'G'),
        (1e6,  'M'),
        (1e3,  'k'),
        (1,    '')
    )

    if is_bytes:
        abbrevs = abbrevs_bytes
    else:
        abbrevs = abbrevs_si

    if d == 1:
        if is_bytes:
            return '1 byte'
        else:
            return '1'

    for factor, suffix in abbrevs:
        if d >= factor:
            break

    return '%.*f %s' % (precision, float(d) / factor, suffix)


try:
    locale.setlocale(locale.LC_ALL, 'en_US')

except locale.Error:

    def pretty_num(d):
        """Prettify num.

        >>> pretty_num(1255000)
        '1255000'
        """
        return "%d" % d

else:
    def pretty_num(d):
        """Prettify num.

        >>> locale.format("%d", 1255000, grouping=True)
        '1,255,000'
        >>> locale.format("%d", 1255000.50, grouping=True)
        '1,255,000'
        >>> pretty_num(1255000)
        '1,255,000'
        """
        return locale.format("%d", d, grouping=True)


def _test():
    """
    When called directly, launching doctests.
    """
    import doctest

    opt =  (doctest.ELLIPSIS |
            doctest.NORMALIZE_WHITESPACE |
            doctest.REPORT_ONLY_FIRST_FAILURE )
            #doctest.IGNORE_EXCEPTION_DETAIL)

    doctest.testmod(optionflags=opt, verbose=False)


if __name__ == '__main__':
    _test()