How to calculate difference between two dates in weeks in python

Question

I\'m trying to calculate the difference between two dates in \"weeks of year\". I can get the datetime object and get the days etc but not week numbers. I can\'t, of course,

Answer 1

The solution above has a bug (I can't add a comment due to low reputation). It doesn't account for hour differences.

# This code has a bug.
monday1 = (d1 - timedelta(days=d1.weekday()))
monday2 = (d2 - timedelta(days=d2.weekday()))

Counter example of 2 dates more than a week apart:

Timestamp1: 1490208193270795 (22 Mar 2017 18:43:13 GMT)
Monday1: 20 Mar 2017 18:43:13 GMT

Timestamp2: 1489528488744290 (14 Mar 2017 21:54:48 GMT)
Monday2: 13 Mar 2017 21:54:48 GMT

Using that code it returns 0 as week diff when it should be 1. Need to zero out the hours/minutes/seconds as well.

Answer 2

How about calculating the difference in weeks between the Mondays within weeks of respective dates? In the following code, monday1 is the Monday on or before d1 (the same week):

from datetime import datetime, timedelta

monday1 = (d1 - timedelta(days=d1.weekday()))
monday2 = (d2 - timedelta(days=d2.weekday()))

print 'Weeks:', (monday2 - monday1).days / 7

Returns 0 if both dates fall withing one week, 1 if on two consecutive weeks, etc.

Answer 3

You're a bit vague on what 'difference in weeks' means exactly. Is 6 days difference one week or zero ? Is eight days difference one week or two ?

In any case, why can't you simply find the difference in another unit (seconds or days) and divide by the appropriate amount, with your prefered rounding for weeks?

Answer 4

You may want to refer the Python CookBook (2005 edition) Recipe 3.3. The following code snippet is from the cookbook, does what you require.

from dateutil import rrule
import datetime
def weeks_between(start_date, end_date):
    weeks = rrule.rrule(rrule.WEEKLY, dtstart=start_date, until=end_date)
    return weeks.count()

Answer 5

This is a very simple solution with less coding everyone would understand.

from datetime import date

d1 = date(year, month, day)
d2 = date(year, month, day)
result = (d1-d2).days//7

Answer 6

To determine how many weeks are spanned by two dates. eg From 3rd Oct to 13th Oct

    October 2015
Mo     5 12 19 26
Tu     6 13 20 27
We     7 14 21 28
Th  1  8 15 22 29
Fr  2  9 16 23 30
Sa  3 10 17 24 31
Su  4 11 18 25

Code:

    import math, datetime

    start_date = datetime.date(2015, 10, 3)
    start_date_monday = (start_date - datetime.timedelta(days=start_date.weekday()))
    end_date = datetime.date(2015, 10, 13)
    num_of_weeks = math.ceil((end_date - start_date_monday).days / 7.0)

Equals 3 weeks.