Given a date and weekday index, the task is to write a Python program to get the date for the given day of the week occurring after the given date. The weekday index is based on the below table:
| Index | Weekday |
|---|---|
| 0 | Monday |
| 1 | Tuesday |
| 2 | Wednesday |
| 3 | Thursday |
| 4 | Friday |
| 5 | Saturday |
| 6 | Sunday |
Examples:
Input : test_date = datetime.datetime(2017, 3, 14), weekday_idx = 4
Output : 2017-03-17
Explanation : 14 March is Tuesday, i.e 1 weekday, 4th weekday is a Friday, i.e 17 March.Input : test_date = datetime.datetime(2017, 3, 12), weekday_idx = 5
Output : 2017-03-18
Explanation : 12 March is Sunday, i.e 6th weekday, 5th weekday in next week is a Saturday, i.e 18 March.
Method #1 : Using timedelta() + weekday()
In this, we subtract the date weekday from the weekday index and then check for required index extracted, then the required day, if negative is summed with 7 and then the resultant number is added to current date using timedelta().
Python3
# Python3 code to demonstrate working of# Next weekday from Date# Using timedelta() + weekday()import datetime# initializing datestest_date = datetime.datetime(2017, 3, 14)# printing original dateprint("The original date is : " + str(test_date)[:10])# initializing weekday indexweekday_idx = 4# computing delta daysdays_delta = weekday_idx - test_date.weekday()if days_delta <= 0: days_delta += 7# adding days to required resultres = test_date + datetime.timedelta(days_delta)# printing resultprint("Next date of required weekday : " + str(res)[:10]) |
The original date is : 2017-03-14 Next date of required weekday : 2017-03-17
Method #2 : Using lambda function
Using the lambda function provides a shorthand and compact solution to the question.
Python3
# Python3 code to demonstrate working of# Next weekday from Date# Using lambda functionimport datetime# initializing datestest_date = datetime.datetime(2017, 3, 14)# printing original dateprint("The original date is : " + str(test_date)[:10])# initializing weekday indexweekday_idx = 4# lambda function provides one liner shorthanddef lfnc(test_date, weekday_idx): return test_date + \ datetime.timedelta(days=(weekday_idx - test_date.weekday() + 7) % 7)res = lfnc(test_date, weekday_idx)# printing resultprint("Next date of required weekday : " + str(res)[:10]) |
The original date is : 2017-03-14 Next date of required weekday : 2017-03-17
Method #3: Using a list comprehension and slicing
In this method, we first generate a list of all dates after the given date up to 7 days later using a list comprehension and the range() function. We add an extra day to the range so that we can slice the list up to 7 days later without including the 8th day.
Next, we use another list comprehension to filter the list to include only dates with the desired weekday.
Finally, we select the nth occurrence of the weekday by indexing the filtered list using [n-1], since the list is zero-indexed but the problem specifies a 1-indexed occurrence.
Python3
from datetime import datetime, timedeltatest_date = datetime(2017, 3, 14)weekday_idx = 4print("The original date is:",str(test_date)[:10])n = 1 # nth occurrence of the weekday (in this case, 1st occurrence)# Generate a list of all dates after the given date up to 7 days laterdates = [test_date + timedelta(days=i) for i in range(8)]# Filter the list to include only dates with the desired weekdayfiltered_dates = [d for d in dates if d.weekday() == weekday_idx]# Select the nth occurrence of the weekdayresult = filtered_dates[n-1]print("Next date of required weekend is:",result.strftime('%Y-%m-%d')) |
The original date is: 2017-03-14 Next date of required weekend is: 2017-03-17
