DayIdxOfMonthsCycle

The class to get the i-th day of a predefined cycle of months. See DayIdxOf... for more details.

Constructor

Creates a DayIdxOfMonthsCycle object.

Required Arguments:

• idx: See DayIdxOf...
• num_months_in_cycle: An integer for the number of months per cycle. This must go into 12 evenly such that the cycle fits evenly in a year (i.e., 12, 6, 4, 3, 2, or 1).

note

• Setting num_months_in_cycle to 12 is equivalent to using DayIdxOfYear
• Setting num_months_in_cycle to 3 is equivalent to using DayIdxOfQuarter
• Setting num_months_in_cycle to 1 is equivalent to using DayIdxOfMonth

Optional Keyword Arguments:

• first_month_of_cycle: A MonthEnum for the first month of the cycle (January, February, March, etc.). Optional, default is January

Methods

See DayIdxOf... for all methods.

Example

Suppose you have 4-month "trimesters" starting in either March, July, or November. Given an input date, you want to find the 66th day of the current trimester. This can be done as follows:

from dateutils import DayIdxOfMonthsCycle, MonthEnum
import datetime

date_modifier = DayIdxOfMonthsCycle(idx=95, num_months_in_cycle=4, first_month_of_cycle=MonthEnum.March)

input_date = datetime.date(2025, 4, 5)
output_date = date_modifier.modify(input_date)
print(output_date) # prints 2025-06-03, 95th day of period "March 1st to June 30th"