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Version: 0.5.x

DateModPipeline (class)

The class to chain together a series of date modifier classes into a pipeline where the pipeline can be used to apply multiple modifications to an input date. A date modifier class is any class in dateutils that starts with "DayIdxOf", "Offset", or "DateModPipeline".

Constructor​

Creates a DateModPipeline object.

Required Arguments:

  • date_modifiers: A sequence of date modifier objects

Methods​

modify​

Modify an input date by applying the series of date modifiers

Required Arguments:

  • date: A datetime.date object representing the input date to modify

Returns: The modified output date as a datetime.date object

with_more_modifiers​

Create a new DateModPipeline with more date modifiers

Required Arguments:

  • date_modifiers: A sequence of date modifier objects to add

Returns: A new DateModPipeline object

get_date_list​

This method modifies the input date, and returns all dates from the input date to the modified date (inclusive), incremented by a DateModifier step.

If the step is positive and start date is less than end date, then it'll return an increasing list of dates starting from the start date. If the step is negative and start date is greater than end date, then it'll return a decreasing list of dates starting from the start date. Otherwise, an empty list is returned

Required Arguments:

  • start_date: A datetime.date object for the start date
  • step: An Offset... object for the increments to take. The offset cannot be zero

Returns: A list of datetime.date objects

Example​

Suppose you have a date and you want to get the first day of the week (starting on Monday), subtract it by 10 days, and get the first day of the month from the result. This can be done as follows:

from dateutils import DateModPipeline, DayIdxOfWeek, DayIdxOfMonth, OffsetDays
import datetime

date_modifier = DateModPipeline([
    DayIdxOfWeek(idx=1, first_day_of_week=DayOfWeekEnum.Monday),
    OffsetDays(offset=-10),
    DayIdxOfMonth(idx=1),
])

input_date = datetime.date(2025, 4, 5)
output_date = date_modifier.modify(input_date)
print(output_date) # prints 2025-03-01

You can also use the same date modifier to get a list of dates from the input date to the modified date (inclusive):

date_list = date_modifier.get_date_list(
    start_date=input_date,
    step=OffsetDays(offset=-1)
)

for date in date_list:
    print(date) 

# prints each date in the list: 
# 2025-04-05, 2025-03-29, 2025-03-22, 2025-03-15, 2025-03-08, 2025-03-01