How can I determine the weekday of a leap day?

January 22, 2022

I am trying to figure out what day of the week the leap day falls under (ex. Sunday, Monday, etc) for each year (ex. 1972 Tuesday) in a range of years.

The code below checks that each year is a leap year and appends it to an array:

import array as year

LeapYear = []

startYear = 1970
endYear = 1980

for year in range(startYear, endYear):
    if (0 == year % 4) and (0 != year % 100) or (0 == year % 400):
        LeapYear.append(year)
        print(year)

>Solution :

You are kind of reinventing the wheel. You can use calendar.isleap to determine if a year is a leap year. To get the zero-indexed day of the week (with the week starting on Mondays), you can use calendar.weekday.

import calendar

days = 'Mon Tue Wed Thu Fri Sat Sun'.split()
start = 1994
end = 2025

for year in range(start, end):
    if calendar.isleap(year):
        day_ix = calendar.weekday(year, 2, 29)
        print(year, days[day_ix])

# prints:
1996 Thu
2000 Tue
2004 Sun
2008 Fri
2012 Wed
2016 Mon
2020 Sat
2024 Thu