def format_and_scale_fraction(numerator, denominator, unit):

    # simple case for small numbers
    if denominator < 1000:
        return '%d / %d %s' % (numerator, denominator, unit)

    # pick a scale
    (scale, suffix) = _pick_scale_and_suffix(denominator)

    # decide how many digits after the decimal to display
    scaled_denominator = denominator / scale
    if scaled_denominator < 10.0:
        fmt = '%1.2f / %1.2f %s%s'
    elif scaled_denominator < 100.0:
        fmt = '%1.1f / %1.1f %s%s'
    else:
        fmt = '%1.0f / %1.0f %s%s'

    # format it
    scaled_numerator = numerator / scale
    return fmt % (scaled_numerator, scaled_denominator, suffix, unit)
Picks a good scale for representing a fraction, and formats it.
dataset/ETHPy150Open Backblaze/B2_Command_Line_Tool/b2/utils.py/format_and_scale_fraction