timesince

timesince.py

#!/usr/bin/env python
from __future__ import division
import sys
from dateutil.parser import parse
from dateutil.relativedelta import relativedelta
from datetime import datetime

from collections import OrderedDict

# from https://en.wikipedia.org/wiki/Year
DAYS_PER_JULIAN_YEAR = 365.25
DAYS_PER_AVERAGE_YEAR = 365.2425 # Google uses this one

def maxstrlen(items):
    return max(len(str(elt)) for elt in items)

def dict_print(d):
    fmt = '{:>%d} {:<%d}' % (maxstrlen(d.values()), maxstrlen(d.keys()))
    print '\n'.join(fmt.format(v,k) for k,v in d.iteritems())

def get_time_since(datestr,total=False):
    if not total:
        rd = relativedelta(datetime.now(), parse(datestr))
        return OrderedDict((key,getattr(rd,key)) for key in
                ('years','months','days','hours','minutes','seconds','microseconds'))
    else:
        td = datetime.now() - parse(datestr)
        return OrderedDict([
            ('total (%s-day Julian) years'
                % DAYS_PER_JULIAN_YEAR,td.days/DAYS_PER_JULIAN_YEAR),
            ('total (%s-day average) years'
                % DAYS_PER_AVERAGE_YEAR,td.days/DAYS_PER_AVERAGE_YEAR),
            ('total days',td.days),
            ('total seconds',td.total_seconds()),
            ])

if __name__ == '__main__':
    datestr = ' '.join(sys.argv[1:])
    dict_print(get_time_since(datestr))
    print ''
    print '... which is'
    dict_print(get_time_since(datestr,total=True))