How to get the Python date object for last Wednesday?

You can get the Python date object for last Wednesday using date arithmetic. The key is calculating how many days back Wednesday was from today, regardless of what day it currently is.

Understanding the Logic

Python's weekday() method returns 0 for Monday, 1 for Tuesday, 2 for Wednesday, and so on. To find last Wednesday, we subtract 2 (Wednesday's index) from today's weekday and use modulo 7 to handle week boundaries ?

Example

from datetime import date, timedelta

today = date.today()
print(f"Today is: {today} ({today.strftime('%A')})")

# Calculate days back to last Wednesday
offset = (today.weekday() - 2) % 7
last_wednesday = today - timedelta(days=offset)

print(f"Last Wednesday was: {last_wednesday}")

Today is: 2024-01-15 (Monday)
Last Wednesday was: 2024-01-10

How the Formula Works

The formula (today.weekday() - 2) % 7 works as follows ?

from datetime import date, timedelta

# Let's see how it works for different days
days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']

for i, day in enumerate(days):
    offset = (i - 2) % 7
    print(f"{day}: go back {offset} days")

Monday: go back 6 days
Tuesday: go back 0 days
Wednesday: go back 1 days
Thursday: go back 2 days
Friday: go back 3 days
Saturday: go back 4 days
Sunday: go back 5 days

Complete Function

Here's a reusable function to get last Wednesday ?

from datetime import date, timedelta

def get_last_wednesday():
    """Returns the date object for the most recent Wednesday."""
    today = date.today()
    offset = (today.weekday() - 2) % 7
    return today - timedelta(days=offset)

# Usage
last_wed = get_last_wednesday()
print(f"Last Wednesday: {last_wed.strftime('%Y-%m-%d (%A)')}")

Last Wednesday: 2024-01-10 (Wednesday)

Conclusion

Use (today.weekday() - 2) % 7 to calculate days back to last Wednesday. The modulo operation handles week boundaries, ensuring the formula works regardless of the current day.