How do I count only weekdays from timedelta in python

Question

I am getting the number of days until the next "billing cycle" (for example) which starts on the nth day of the month:

from dateutil.relativedelta import relativedelta

dt = datetime.utcnow() + relativedelta(months=1,day=schedule.cycle_start)
days_till_next_cycle = dt - datetime.utcnow()

Where schedule.cycle_start is going to be something like 2 for the second day of the month.

This works... But:

How do I find the number of weekdays in that timedelta.

I took a look at https://pypi.python.org/pypi/BusinessHours/ and could not find any documentation.

I also saw this: Business days in Python which linked me to the link above and rolling my own. It's also been 4 years since that post and I was hoping there might be a simpler way?

Rob Parker · Accepted Answer · 2014-01-16T03:48:13.487

8

With rrule I was able get the following using the dt definition from above:

    from dateutil.rrule import *
    number_weekdays = rrule(WEEKLY, byweekday=(MO,TU,WE,TH,FR), dtstart=datetime.utcnow(),until=dt).count()

edited Jan 16 '14 at 03:48

answered Jan 16 '14 at 03:26

Rob Parker

503
4
10

Nice answer! Btw, `rrule`s also have a [count method](http://labix.org/python-dateutil#head-cf004ee9a75592797e076752b2a889c10f445418). – unutbu Jan 16 '14 at 03:41
Very cool! If say I wanted to only calculate by `Mo`,`Tu`,`Th`,`Fr` could I just leave out `we` out of the tuple? And it would just work? (If for example the business was not open on wednesdays?) – Johnston Jan 16 '14 at 03:48
@RobParker I believe the answer for my comment above is yes, as I just tried it and it worked. Just double checking though. – Johnston Jan 16 '14 at 03:58

score 2 · Answer 2 · answered Jun 30 '14 at 16:09

Here a simple function that compute the number of business days between 2 dates:

def business_days(since, until):
    since_isoweekday = since.isoweekday() + 1
    return len([x for x in range(since_isoweekday,
                                 since_isoweekday + (until - since).days)
                if x % 7 not in [0, 6]])

not in [0, 6] stands for saturday and sunday.

Some tests:

>>> since = datetime.datetime(2014, 6, 2)
>>> until = datetime.datetime(2014, 6, 30)
>>> business_days(since, until)
20
>>> since = datetime.datetime(2014, 6, 25)
>>> until = datetime.datetime(2014, 7, 4)
>>> business_days(since, until)
7

How do I count only weekdays from timedelta in python

2 Answers2