How to calculate months left to particular date?

Question

In my django app, I have some date. I need to count how many months left to this date, using full (rounded) months. eg: today is 19/02/2015 (february), my "search" date is 04/08/2015. Difference should be 6. How can I get a proper value?

Answer 1

from datetime import datetime,timedelta
from calendar import monthrange

today = datetime.today()
dt = "04/08/2015"

fut = datetime.strptime(dt, "%d/%m/%Y")
diff = 0
while today <= fut:
    today += timedelta(days=monthrange(today.day,today.month)[1])
    diff += 1
print(diff)
6

Without importing calender we can increment a count everytime we see a new month:

from datetime import datetime,timedelta

today = datetime.today() 
dt = "09/08/2015"

fut = datetime.strptime(dt, "%d/%m/%Y")
diff = 0
while today <= fut:
    mon = today.month
    today += timedelta(days=1)
    if today.month != mon:
        diff += 1
print(diff)
6

If you want to make the future day the last day of the month:

from datetime import datetime, timedelta
from calendar import monthrange

today = datetime.today()
dt = "02/08/2015"

fut = datetime.strptime(dt, "%d/%m/%Y")
fut = fut + timedelta(days=monthrange(fut.day,fut.month)[1]-fut.day)
diff = 0
while today < fut:
    mon = today.month
    today += timedelta(days=1)
    if today.month != mon:
        diff += 1
print(diff)

This is purposely inaccurate to allow for rounding as required, all we care about are the amount of different months we encounter.