On Thu, 05 Apr 2018 22:03:07 -0600, Jason Friedman wrote:
>> > > I've written a function to return the months between date1 and >> > > date2 >> but >> > > I'd like to know if anyone is aware of anything in the standard >> > > library to do the same? For bonus points, does anyone know if >> > > postgres can do the same (we use a lot of date/time funcitons in >> > > postgres, already, but didn't see this problem addressed). >> >> > >> > It's probably better to write the function yourself according to what >> > makes sense in your use-case, and document its behaviour clearly. >> >> > I suggest using the dateutil module ( > https://pypi.python.org/pypi/python-dateutil) before writing your own. I'm not seeing a "months between" function in dateutil. Have I missed something? The question of how many months are between two dates is hard to answer. For example: - between Jan 1 and Feb 1 is clearly one month (31 days); - unless you think all months should be 30 days, in which case its one month and one day; - giving one month from Jan 1 as Jan 31, which seems weird; - either way, the period between Feb 1 and Mar 1 is only four weeks and so obviously less than one month; - unless you think a month is four weeks precisely; - in which case it is one month between Jan 1 and Jan 29; - one month forward from Jun 30 is clearly Jul 30; - but one month back from Jul 31 is either Jun 30 or Jul 1; - instead of counting days, with all the difficulty that causes, we could just count how many times the month changes; - in which case, Jan 31 to Feb 1 is one month. I wish the calendar designers had made the year 13 months of exactly 4 weeks each, with one intercalary day left over (two in leap years). Half a year becomes exactly 6 months and two weeks; a quarter of a year becomes three months and one week. A third is a bit more than four weeks. Date calculations would be much simpler, with only one (or two in leap years) special case, the intercalary day, instead of 36. -- Steve -- https://mail.python.org/mailman/listinfo/python-list
