humanize_time.py

#!/usr/bin/env python

INTERVALS = [1, 60, 3600, 86400, 604800, 2419200, 29030400]
NAMES = [('second', 'seconds'),
         ('minute', 'minutes'),
         ('hour',   'hours'),
         ('day',    'days'),
         ('week',   'weeks'),
         ('month',  'months'),
         ('year',   'years')]

def humanize_time(amount, units):
   '''
      Divide `amount` in time periods.
      Useful for making time intervals more human readable.

      >>> humanize_time(173, "hours")
      [(1, 'week'), (5, 'hours')]
      >>> humanize_time(17313, "seconds")
      [(4, 'hours'), (48, 'minutes'), (33, 'seconds')]
      >>> humanize_time(90, "weeks")
      [(1, 'year'), (10, 'months'), (2, 'weeks')]
      >>> humanize_time(42, "months")
      [(3, 'years'), (6, 'months')]
      >>> humanize_time(500, "days")
      [(1, 'year'), (5, 'months'), (3, 'weeks'), (3, 'days')]
   '''
   result = []

   unit = map(lambda a: a[1], NAMES).index(units)
   # Convert to seconds
   amount = amount * INTERVALS[unit]

   for i in range(len(NAMES)-1, -1, -1):
      a = amount // INTERVALS[i]
      if a > 0: 
         result.append( (a, NAMES[i][1 % a]) )
         amount -= a * INTERVALS[i]

   return result

if __name__ == "__main__":
    import doctest
    doctest.testmod()