Get last friday of each month in python

Question

I want last friday of each month for upcoming three months.

Friday_date = datetime.date.today()

    while Friday_date.weekday() != 4:
        Friday_date += datetime.timedelta(1)

This gives me the nearest friday. I want to make sure this is the last friday of this month so that i can add 28 days to get next friday.

Answer 1

The easiest way to do this is to use the module dateutil:

>>> from dateutil.relativedelta import FR, relativedelta
>>> datetime.date.today()+relativedelta(day=31, weekday=FR(-1))
datetime.date(2021, 6, 25)

Don't assume you can get the last Friday of subsequent months just by adding 28 days. It won't always work. Adding 28 days to the last Friday of February 2024 gives you this:

>>> datetime.date(2024,2,1)+relativedelta(day=31, weekday=FR(-1), days=28)
datetime.date(2024, 3, 22)

but the last Friday of that month is 29 March. Let dateutil do that correctly for you:

>>> datetime.date(2024,2,1)+relativedelta(day=31, weekday=FR(-1), months=1)
datetime.date(2024, 3, 29)

Answer 2

If needed with standard library only, here is with calendar and datetime:

import calendar
from datetime import date

today = date.today()
year, month = today.year, today.month

n_months = 4
friday = calendar.FRIDAY

for _ in range(n_months):
    # get last friday
    c = calendar.monthcalendar(year, month)
    day_number = c[-1][friday] or c[-2][friday]

    # display the found date
    print(date(year, month, day_number))

    # refine year and month
    if month < 12:
        month += 1
    else:
        month = 1
        year += 1

where the line c[-1][friday] or c[-2][friday] first checks the last week of the month: is Friday nonzero there? if so take it, else look at the week before where there must be a Friday.

This prints

2021-06-25
2021-07-30
2021-08-27
2021-09-24