Calculate annualized rate of change — annualize

Computes the annualized rate of change from paired start and end values over a given time interval, annualizing according to the specified unit.

Usage

annualize_change(
  start_values,
  end_values,
  time_elapsed,
  time_unit = c("daily", "weekly", "monthly", "quarterly", "annually"),
  year_length = 365.2425
)

Arguments

start_values: Numeric scalar or vector of positive start values.
end_values: Numeric scalar or vector of positive end values. If any of start_values, end_values, or time_elapsed is a scalar, it is recycled to the common length; otherwise, lengths must be compatible.
time_elapsed: Numeric scalar or vector of elapsed time in time_unit between start and end. If scalar, it is recycled.
time_unit: One of "daily", "weekly", "monthly", "quarterly", "annually".
year_length: Days per year used when time_unit is "daily" (and to derive weeks/year when time_unit is "weekly"). Defaults to 365.2425 (Gregorian average year).

Value

A numeric scalar or vector of annualized rates, same length as the recycled inputs.

Examples

# Scalar (monthly): from 100 to 103 over 1 month -> annualized rate
annualize_change(100, 103, time_elapsed = 1, time_unit = "monthly")
#> [1] 0.4257609

# Vectorized (quarterly): scalar start recycled to match end/time vectors
annualize_change(
  start_values = 100,
  end_values   = c(101, 98, 120),
  time_elapsed = c(1, 2, 3),
  time_unit    = "quarterly"
)
#> [1]  0.04060401 -0.03960000  0.27519028

# Weekly with exact 52-week convention (52 * 7 = 364 days)
annualize_change(
  start_values = 100,
  end_values   = 102,
  time_elapsed = 4,
  time_unit    = "weekly",
  year_length  = 364
)
#> [1] 0.2936066