intervalDivideEquallyDate

Signature

intervalDivideEquallyDate(start: string, end: string, n: number): { start: string; end: string; }[]

import { intervalDivideEquallyDate } from "@northguild/gmt/plain/interval";

Split a date interval into n equal-length sub-intervals.

• Returns an array of n { start, end } records that tile the original interval, each record’s end equal to the next record’s start.
• PlainDate has no fractional-day representation, so each internal boundary is rounded to the nearest whole day — when totalDays isn’t evenly divisible by n, the resulting sub-intervals differ by at most one day rather than being mathematically exact.
• n === 1 returns the original interval unchanged, as a single-element array.
• A zero-length interval (start === end) returns n identical zero-length sub-intervals.
• Returns [] when n is not a positive integer, or on invalid input (unparseable start/end, start > end).
• Accepts GMT calendar-annotated PlainDate strings — E5 (issue #78). start and end must carry the same calendar tag (or both be bare ISO); a mismatch returns [] (E5 decision of record D4). Internal boundaries are computed in whole days (calendar-independent), then re-formatted in the shared calendar.

Parameters

Parameter	Type	Description
start	string	ISO PlainDate string for the interval start, optionally calendar-annotated
end	string	ISO PlainDate string for the interval end, optionally calendar-annotated
n	number	number of equal sub-intervals to produce (positive integer)

Returns

array of n { start, end } records, or [] on invalid input / mismatched calendars

Examples

intervalDivideEquallyDate("2024-01-01", "2024-01-05", 4) // [{ start: "2024-01-01", end: "2024-01-02" }, { start: "2024-01-02", end: "2024-01-03" }, { start: "2024-01-03", end: "2024-01-04" }, { start: "2024-01-04", end: "2024-01-05" }]
intervalDivideEquallyDate("2024-01-01", "2024-01-10", 3) // [{ start: "2024-01-01", end: "2024-01-04" }, { start: "2024-01-04", end: "2024-01-07" }, { start: "2024-01-07", end: "2024-01-10" }]
intervalDivideEquallyDate("2024-01-01", "2024-01-10", 1) // [{ start: "2024-01-01", end: "2024-01-10" }]
intervalDivideEquallyDate("2024-01-01", "2024-01-01", 3) // [{ start: "2024-01-01", end: "2024-01-01" }, { start: "2024-01-01", end: "2024-01-01" }, { start: "2024-01-01", end: "2024-01-01" }]
intervalDivideEquallyDate("2024-01-01", "2024-01-10", 0) // []
intervalDivideEquallyDate("invalid", "2024-01-10", 3) // []

Source

plain/interval/intervalDivideEquallyDate.ts