For American numbers

[Nick Coghlan]

Scott David Daniels wrote:
> Kind of fun exercise (no good for British English).
> 
>     def units(value, units='bytes'):
>         magnitude = abs(value)
>         if magnitude >= 1000:
>             for prefix in :
>                 magnitude /= 1000.
>                 if magnitude < 1000.:
>                     break
>         elif magnitude < 1:
>             for prefix in :
>                 magnitude *= 1000.
>                 if magnitude >= 1.0:
>                     break
>             if magnitude < .001:
>                 return 'zero %s' % units
>         else:
>             prefix = ''
>         if value < 0:
>             return '-%.3f %s%s' % (magnitude, prefix, units)
>         return '%.3f %s%s' % (magnitude, prefix, units)
> 
> --Scott David Daniels
> Scott.Daniels at Acm.Org
> 

Because I can't resist generalising this. . .

def units(value, units='bytes', base=1000.0,
           super_prefixes = ('kilo mega giga tera peta ' 

                             'exa zetta yotta').split(),
           sub_prefixes = ('milli micro nano pico femto '
                           'atto zepto yocto').split()):
     magnitude = abs(value)
     if magnitude >= base:
         for prefix in super_prefixes:
             magnitude /= base
             if magnitude < base:
                 break
     elif magnitude < 1.0:
         for prefix in sub_prefixes:
             magnitude *= base
             if magnitude >= 1.0:
                 break
         if not sub_prefixes or magnitude < .001:
             return 'zero %s' % units
     else:
         prefix = ''
     if value < 0:
         return '-%.3f %s%s' % (magnitude, prefix, units)
     return '%.3f %s%s' % (magnitude, prefix, units)

def bytecount(value):
     # Should check if these prefixes are right. . .
     return units(value, 'bytes', 1024.0,
            'kibi mebi gibi tebi pebi ebi zebi yobi'.split(), [])

Py> for i in range(1, 28, 3):
...     print units(10**i)
...     print bytecount(10**i)
...
10.000 bytes
10.000 bytes
10.000 kilobytes
9.766 kibibytes
10.000 megabytes
9.537 mebibytes
10.000 gigabytes
9.313 gibibytes
10.000 terabytes
9.095 tebibytes
10.000 petabytes
8.882 pebibytes
10.000 exabytes
8.674 ebibytes
10.000 zettabytes
8.470 zebibytes
10.000 yottabytes
8.272 yobibytes

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at email.com   |   Brisbane, Australia
---------------------------------------------------------------
             http://boredomandlaziness.skystorm.net