Adding days to a given date (Consider working days only)

Some times, we may be getting requirements like finding the 10^th working day from today. Most common scenarios are for sending email reminders considering only business days. For this we will have to add days to a particular date, excluding weekends.

To add only working days to a date, we have to identify the Saturdays and Sundays within the range using strftime('%w') function. This functions returns weekday numbers. For Sunday, the number returned is 0 and for Saturday it is 6. Then using a while loop we can check each day within the range for weekends and skip those.
Code sample provided below.

import datetime

def findWorkingDayAfter (startDate, daysToAdd):
    #0 - Sunday and 6 Saturday are to be skipped
    workingDayCount = 0    
    while workingDayCount < daysToAdd:
        startDate += datetime.timedelta(days=1)
        weekday = int(startDate.strftime('%w'))
        if (weekday != 0 and weekday != 6):
            workingDayCount += 1
    
    return startDate

startDate = datetime.datetime(2022, 1, 15)
daysToAdd = 10
print(findWorkingDayAfter(startDate, daysToAdd))

On running the above sample we will get the below output.

Output: 2022-01-28 00:00:00

By slightly modifying the above function, we can add logic to skip holidays list also. Keep list of holidays in a tuple in the format (month, day). Then add an additional check to exclude those values.

Note that startDate.strftime('%m') and startDate.strftime('%d') return the values padded with a 0. So the list should also have padded numbers as in sample below.

import datetime

def findWorkingDayAfter (startDate, daysToAdd):
    #0 - Sunday and 6 Saturday are to be skipped
    workingDayCount = 0
    holidays = ( '01-20', '01-23', '02-15', '03-01' )
    while workingDayCount < daysToAdd:
        startDate += datetime.timedelta(days=1)
        weekday = int(startDate.strftime('%w'))
        if (weekday != 0 and weekday != 6):
            currentday = str(startDate.strftime('%m')) + '-' + str(startDate.strftime('%d'))
            if(not(any( currentday in day for day in holidays))):
                workingDayCount += 1
    
    return startDate

startDate = datetime.datetime(2022, 1, 15)
daysToAdd = 10
print(findWorkingDayAfter(startDate, daysToAdd))

On running the above sample we will get the output.

Output: 2022-01-31 00:00:00

We have marked 20 and 23 of January as holidays. Since 23 is already a weekend, only 20 is skipped from the first example and we get the output as 31-Jan-2022 (29 and 30 are weekends).