Isoweekday() Function Of Datetime.date Class In Python

Last Updated : 31 Aug, 2021

isoweekday() is a function that returns an integer that tells the given date falls on. The integer it returns represents a day according to the table given below.

Syntax: datetime.isoweekday()

Return Value: an integer in range of [1,7]

Integer Returned	Day of the week
1	Monday
2	Tuesday
3	Wednesday
4	Thursday
5	Friday
6	Saturday
7	Sunday

Example 1: This program grabs the date using the DateTime module and tells the day of the date.

Python3

# importing the datetime module
import datetime
 
# Creating an list which will
# be  used to retrieve the day of the
# week using the return value of the
# isoweekday() function
DaysList  = ["None",
              "Monday",
            "Tuesday",
            "Wednesday",
            "Thursday",
            "Friday",
            "Saturday",
            "Sunday"]
 
# Using the function today()
# to get today's date
CurrentDate = datetime.date.today()
print("Current Date is :", CurrentDate)
 
# Using the isoweekday() function to
# retrieve the day of the given date
day = CurrentDate.isoweekday()
print("The date", CurrentDate, "falls on",
      DaysList[day])

Output:

Current Date is : 2021-08-18
The date 2021-08-18 falls on Wednesday

Example 2: In this example, we will take the user's input for a date and will return the day it falls on.

Python3

# importing the datetime module
import datetime

# Creating an dictionary with the return
# value as keys and the day as the value
# This is used to retrieve the day of the week
# using the return value of the isoweekday()
# function
DaysList = ["None",
            "Monday",
            "Tuesday",
            "Wednesday",
            "Thursday",
            "Friday",
            "Saturday",
            "Sunday"]

# Getting the  user's input
day = 18
month = 9
year = 2020

# Creating the datetime object for the user's
# input by using the date() function of datetime 
# class
Date = datetime.date(year, month, day)

# Using the isoweekday() function
# to retrieve the day of the given date
day = Date.isoweekday()

print("The given date", Date, "falls on", 
      DaysList[day])

Output:

The given date 2020-09-18 falls on Friday

Example 3: In this example, we will take the user's input for the date and the day that it falls on and return if that's true or not

Python3

# importing the datetime module
import datetime

# Creating an dictionary with the return
# value as keys and the day as the value
# This is used to retrieve the day of the week
# using the return value of the isoweekday()
# function
DaysList = ["None",
            "Monday",
            "Tuesday",
            "Wednesday",
            "Thursday",
            "Friday",
            "Saturday",
            "Sunday"]

# Getting the  user's input
day = 1
month = 1
year = 2021
day_fallen = "Friday"

# Creating the datetime object for the user's
# input by using the date() function of datetime
# class
Date = datetime.date(year, month, day)

# Using the isoweekday() function
# to retrieve the day of the given date
day = Date.isoweekday()

# Checking if the day is matching the user's
# day
if day_fallen.lower() == DaysList[day].lower():
    print("Yes, your given date", Date,
          "falls on your expected day i.e ",
          DaysList[day])
else:
    print("No, your given date", Date, "falls on",
          DaysList[day],
          "but not on", day_fallen)