CODEWITHSUNDEEP
pythonpython-2.7
Alban Barbosa
Alban Barbosa

Reputation: 9

Calculate with date, without import dateutil

from datetime import datetime
from dateutil import relativedelta
date1 = datetime.strptime(str('2011-08-15 12:00:00'), '%Y-%m-%d %H:%M:%S')
date2 = datetime.strptime(str('2012-02-15'), '%Y-%m-%d')
r = relativedelta.relativedelta(date2, date1)
r.months

The code above does the trick for me but i don't want to import dateutil. Does anyone have an example for me without looping?

I want to deduct two dates from each other and i want to know the difference in months between the two dates in whole months.

Upvotes: 1

Views: 741

Answers (2)

norok2
norok2

Reputation: 26886

Interestingly enough, your code outputs to: 5 which means, as suggested in the comments, that you are probably interested in the duration of each month and you do not want to round your results. Unfortunately the timedelta object will not work for you in this case because by definition, a time difference does not hold the information you need to obtain the duration of the months of interest to you.

You should probably take a look here: Python: Difference of 2 datetimes in months where they discuss a solution using calendar instead of dateutil.

Otherwise, if you are happy with an approximated (and rounded) estimate, you could go close enough by doing:

DAYS_PER_MONTH = 30  # or 365.0 / 12.0 for more precision
datetime_diff = date2 - date1
print(datetime_diff.days / DAYS_PER_MONTH)  # '//' for floored result

If you want to get back to some code that works with your data (but not with all data, because of e.g. leap years, leap seconds, etc.) have a look here:

MONTH_NUM_DAYS = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
YEAR_LENGTH = 365.25  # average year duration, including leap years

def num_days_in_months(
        begin_month, end_month, month_duration=MONTH_NUM_DAYS):
    begin_month, end_month = sorted((begin_month, end_month))
    return sum(month_duration[begin_month:end_month])

def get_num_months(begin_date, end_date, num_days_per_year=YEAR_LENGTH):
    begin_month = begin_date.month
    end_month = end_date.month
    month_diff = abs(end_month - begin_month)
    num_days = (end_date - begin_date).days
    num_days_within_year = num_days % num_days_per_year
    num_months = num_days // num_days_per_year
    num_days_max = num_days_in_months(begin_month, end_month)
    print(num_months, month_diff)
    if num_days_within_year < num_days_max:
        num_months += month_diff - 1
    else:
        num_months += month_diff
    return num_months

Upvotes: 0

vivi
vivi

Reputation: 334

Seems this post helps: How do I find the time difference between two datetime objects in python?

simply do a substraction on two datetime obj, then you can get what detail you want in the diff.

Upvotes: 1

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