Engineering format function

format_eng.py

import math

def format_eng(number, places=2, force_exponent=None, use_si=False, use_unicode=False, use_latex=False, return_components=False, strip_zeros=True, unit=None, pos_sign=False):
    si_lookup = {
        24: 'Y', 21: 'Z',
        18: 'E', 15: 'P', 12: 'T',
        9: 'G', 6: 'M', 3: 'k',
        -3: 'm', -6: 'μ', -9: 'n',
        -12: 'p', -15: 'f', -18: 'a',
        -21: 'z', -24: 'y',
        }
    if number == 0:
        result = "%.*f" % (places, 0)
        if '.' in result and strip_zeros:
            result = result.rstrip('0').rstrip('.')
        if unit is not None:
            result += " " + unit
        return result
    abs_value = abs(number)
    exponent = int(math.log10(abs_value))
    engr_exponent = exponent - (exponent % 3)
    if force_exponent is not None:
        engr_exponent = force_exponent
    value = abs_value / (10**engr_exponent)
    if value < 1.0 and force_exponent is None:
        value *= 1000.0
        engr_exponent -= 3
    if number > 0 and pos_sign:
        sign = '+'
    elif number < 0:
        sign = '-'
    else:
        sign = ''
    if sign == '-' and use_unicode:
        sign = '–' # en-dash
    elif sign == '-' and use_latex:
        sign = '$-$'
    if return_components:
        return sign, value, engr_exponent
    else:
        result = "%s%.*f" % (sign, places, value)
        if '.' in result and strip_zeros:
            result = result.rstrip('0').rstrip('.')

        if engr_exponent != 0:
            if use_si and engr_exponent in si_lookup:
                result += ' %s' % (si_lookup[engr_exponent])
                if use_latex and 'μ' in result:
                    result = result.replace('μ', '$\mathrm{\mu}$')
            elif use_unicode:
                result += '×10' + ''.join(dict(zip("-0123456789", "⁻⁰¹²³⁴⁵⁶⁷⁸⁹")).get(c, c) for c in "%d" % engr_exponent)
            elif use_latex:
                result += r'$\times 10^{%d}$' % (engr_exponent)
            else:
                result += 'e%d' % (engr_exponent)
    if unit is not None:
        if ' ' not in result:
            result += ' '
        result += unit
    return result