I'm trying to get a list of months in the given range. Specifically, given the range 2015-12-31 - 2016-01-01, I want to get the list 2015-12 and 2016-01.
I'm using dateutil's rrule, but the until parameter isn't really helping since it seems to be looking for complete months.
E.g.:
from dateutil.relativedelta import relativedelta
from dateutil.rrule import rrule, MONTHLY
list(rrule(MONTHLY, dtstart=datetime(2015, 12, 31), until=datetime(2016,01,01)))
This only returns [datetime.datetime(2015, 12, 31, 0, 0)], not [datetime.datetime(2015, 12, 31, 0, 0), datetime.datetime(2016, 01, 01, 0, 0)]
Likewise, I want the same output for any start day in December, and any end day in January. That's to say, I only care about the fact that the months are 2015-12 and 2016-01. The day part is not important for me, but I only want a single datetime per month (a maximum of 2 for these inputs, with any value for the day component).
Is there a simple solution, or will I have to increment DAILY and build my own set of months?
The reason your list(rrule(MONTHLY, dtstart=datetime(2015, 12, 31), until=datetime(2016,01,01))) isn't returning January is because there isn't a month (based on the MONTHLY parameter) between December 31 and January 1.
Since you don't need the day component for this, I'm going to perform a little date manipulation:
def date_list(start, end):
start = datetime.date(start.year, start.month, 1)
end = datetime.date(end.year, end.month, 1)
dates = [dt for dt in rrule(MONTHLY, dtstart=start, until=end)]
return dates
What this does is accept any start and end date and then resets both of those to be the first of the month. This ensures that a full month exists. It will return a list of dates and each date will be the first of the month.
For example, with your input
>>> print date_list(datetime.date(2015,12,28), datetime.date(2016,1,1))
[datetime.datetime(2015, 12, 1, 0, 0), datetime.datetime(2016, 1, 1, 0, 0)]
With the same month:
>>> print date_list(datetime.date(2015,12,28), datetime.date(2015,12,31))
[datetime.datetime(2015, 12, 1, 0, 0)]
With an invalid range (end before start):
>>> print date_list(datetime.date(2015,12,28), datetime.date(2015,11,30))
[]
With a longer range:
>>> print date_list(datetime.date(2015,12,28), datetime.date(2016,8,3))
[datetime.datetime(2015, 12, 1, 0, 0),
datetime.datetime(2016, 1, 1, 0, 0),
datetime.datetime(2016, 2, 1, 0, 0),
datetime.datetime(2016, 3, 1, 0, 0),
datetime.datetime(2016, 4, 1, 0, 0),
datetime.datetime(2016, 5, 1, 0, 0),
datetime.datetime(2016, 6, 1, 0, 0),
datetime.datetime(2016, 7, 1, 0, 0),
datetime.datetime(2016, 8, 1, 0, 0)]