Best way to accurately get the number of months between two dates spanning different years

Question

I have the need to be able to accurately find the number of months between two dates even when they span different years. I have the below solution which I got from this StackOverflow thread but it fails at when the dates span different years.

works when it spans one year

from datetime import datetime
from dateutil.relativedelta import relativedelta

date1 = datetime.strptime('2010-01-01', '%Y-%m-%d')
date2 = datetime.strptime('2010-12-01', '%Y-%m-%d')
diff = relativedelta(date2, date1)
number_of_months = diff.months
print(number_of_months) # 11

fails when it spans multiple years

from datetime import datetime
from dateutil.relativedelta import relativedelta

date1 = datetime.strptime('2010-01-01', '%Y-%m-%d')
date2 = datetime.strptime('2012-02-01', '%Y-%m-%d')
diff = relativedelta(date2, date1)
number_of_months = diff.months
print(number_of_months) # 1

In light of this, I considered the following solution:

from datetime import datetime
from dateutil.relativedelta import relativedelta


def month_diff(date1, date2):
    if date1.year == date2.year:
        diff = relativedelta(date2, date1)
        number_of_months = diff.months
    else:
        num_of_days = (date2 - date1).days
        number_of_months = num_of_days//30
    print(number_of_months)


date1 = datetime.strptime('2010-01-01', '%Y-%m-%d')
date2 = datetime.strptime('2010-12-01', '%Y-%m-%d')

date3 = datetime.strptime('2010-01-01', '%Y-%m-%d')
date4 = datetime.strptime('2012-02-01', '%Y-%m-%d')

month_diff(date1, date2) # 11
month_diff(date3, date4)  # 25

My question, therefore, is, is there a better solution than what I currently have?

score 2 · Accepted Answer · answered Dec 10 '18 at 08:02

What about

from datetime import datetime
from dateutil.relativedelta import relativedelta

date1 = datetime.strptime('2010-01-01', '%Y-%m-%d')
date2 = datetime.strptime('2012-02-01', '%Y-%m-%d')
diff = relativedelta(date2, date1)
number_of_months = 12 * diff.years + diff.months

Best way to accurately get the number of months between two dates spanning different years

1 Answers1