isoweekday()

from datetime import date

dt = date.today()
print(dt.isoweekday())

2

from datetime import datetime

dt = datetime(2019, 12, 31)
print(dt.isoweekday())

2

from datetime import date

dt = date.today()
print(dt.weekday())      # Monday = 0
print(dt.isoweekday())   # Monday = 1

Example 1: Determine if a Date Falls on a Weekend

from datetime import date

dt = date(2024, 9, 14)
if dt.isoweekday() in [6, 7]:
    print(f"{dt} is a weekend.")
else:
    print(f"{dt} is a weekday.")

2024-09-14 is a weekend.

Example 2: Check Day for Next 7 Days

from datetime import date, timedelta

today = date.today()
for i in range(7):
    future_date = today + timedelta(days=i)
    print(future_date, future_date.isoweekday())

2024-09-14 6
2024-09-15 7
2024-09-16 1                                        
2024-09-17 2                                        
2024-09-18 3
2024-09-19 4
2024-09-20 5

Example 4: Listing All Mondays in a Given Month

We can generate a list of all Mondays in a specific month using isoweekday().

from datetime import date, timedelta

def get_weekdays_in_month(year, month, weekday):
    # weekday: 1=Monday, 2=Tuesday, ..., 7=Sunday
    dates_list = []
    current_date = date(year, month, 1)
    while current_date.month == month:
        if current_date.isoweekday() == weekday:
            dates_list.append(current_date)
        current_date += timedelta(days=1)
    return dates_list

mondays_in_february_2025 = get_weekdays_in_month(2025, 2, 1)
for monday in mondays_in_february_2025:
    print(monday)

Example 5: Comparing isoweekday() and weekday() Methods

The difference between isoweekday() and weekday() is in their numbering system. The isoweekday() method returns 1 for Monday through 7 for Sunday, whereas weekday() returns 0 for Monday through 6 for Sunday.

from datetime import date

dt = date(2025, 2, 9)  # February 9, 2025
print(f"weekday(): {dt.weekday()}")      # Output: 6
print(f"isoweekday(): {dt.isoweekday()}")  # Output: 7

Use Case: Task Scheduling on Specific Weekdays

We can use isoweekday() to check the current day and execute corresponding tasks in an application where specific tasks run on particular days.

from datetime import date

today = date.today()
if today.isoweekday() == 1:  # Monday
    print("Execute Monday's tasks.")
elif today.isoweekday() == 5:  # Friday
    print("Prepare for the weekend.")
else:
    print("Continue with the usual workflow.")

Conclusion

The isoweekday() method is a simple yet powerful tool for handling date-related logic, especially in scheduling and reporting applications. By leveraging this method, we can efficiently classify days, generate date-based reports, and automate tasks based on the day of the week.