swing_schedule: Build a swing/recovery projection schedule

In enrollcast: Project School Enrollment with Grade Progression Ratios

Build a swing/recovery projection schedule

Description

Assembles a per-year project_enrollment() schedule for a school passing through a temporary relocation ("swing"): enrollment is held flat at the depressed observed level during the swing (identity steps), scaled by year-over-year recovery multipliers for the recovery window (diagonal steps), then projected with the grade progression ratio method (the normal projection matrix) for the remaining years.

Usage

swing_schedule(
  ratios,
  horizon,
  swing_years,
  recovery,
  entry = NULL,
  grade_order = NULL
)

Arguments

ratios	A data frame or data-frame subclass with columns grade_from, grade_to, and ratio, as returned by progression_ratios(). grade_from and grade_to must not be missing. ratio must be numeric, non-negative, and finite; an infinite ratio (from a zero-enrollment feeder) is rejected, while NA/NaN ratios (e.g. from sparse history) are kept in the matrix with a warning.
horizon	Number of years to project (a positive integer).
swing_years	Number of leading years the school is swinging (a non-negative integer); enrollment is held flat at base.
recovery	Recovery multipliers applied for one year each, immediately after the swing and compounding on the prior year: a numeric vector (whole-school, one multiplier per recovery year) or a grade-by-year numeric matrix (one row per grade). Values must be finite, non-missing, and non-negative. Named matrix rows are matched and reordered by grade; unnamed rows are interpreted in projection grade order. Use numeric(0) for no recovery window.
entry	Exogenous entry-grade enrollment for the normal grade progression ratio years only: one finite, non-missing, non-negative numeric value for each of the horizon - swing_years - length(recovery) years after recovery. Must be empty when there are no normal years.
grade_order	Optional character vector giving the low-to-high grade order. If omitted, the order is reconstructed from the transition chain. Every non-entry grade in grade_order must appear as a grade_to in ratios. Must not contain duplicates or missing values.

Value

A list of horizon projection steps suitable for the schedule argument of project_enrollment().

Examples

ratios <- data.frame(
  grade_from = c("K", "1"), grade_to = c("1", "2"), ratio = c(0.92, 0.97)
)
schedule <- swing_schedule(ratios,
  horizon = 6, swing_years = 2,
  recovery = c(1.10, 1.10, 1.05), entry = 130
)
project_enrollment(c(K = 80, `1` = 66, `2` = 60), schedule = schedule)

enrollcast documentation built on Aug. 27, 2026, 1:08 a.m.