Calculate age between two dates — age

This function calculates the age between two dates using functions in lubridate. It calculates age in either years or months.

Usage

age_calculate(
  start,
  end = if (lubridate::is.Date(start)) Sys.Date() else Sys.time(),
  units = c("years", "months"),
  round_down = TRUE
)

Arguments

start: A start date (e.g. date of birth) which must be supplied with Date or POSIXct or POSIXlt class. base::as.Date(), lubridate::dmy() and as.POSIXct() are examples of functions which can be used to store dates as an appropriate class.
end: An end date which must be supplied with Date or POSIXct or POSIXlt class. Default is Sys.Date() or Sys.time() depending on the class of start.
units: Type of units to be used. years and months are accepted. Default is years.
round_down: Should returned ages be rounded down to the nearest whole number. Default is TRUE.

Value

A numeric vector representing the ages in the given units.

Examples

library(lubridate)
#> 
#> Attaching package: ‘lubridate’
#> The following objects are masked from ‘package:base’:
#> 
#>     date, intersect, setdiff, union
birth_date <- lubridate::ymd("2020-02-29")
end_date <- lubridate::ymd("2022-02-21")
age_calculate(birth_date, end_date)
#> [1] 1
age_calculate(birth_date, end_date, units = "months")
#> [1] 23

# If the start day is leap day (February 29th), age increases on 1st March
# every year.
leap1 <- lubridate::ymd("2020-02-29")
leap2 <- lubridate::ymd("2022-02-28")
leap3 <- lubridate::ymd("2022-03-01")

age_calculate(leap1, leap2)
#> [1] 1
age_calculate(leap1, leap3)
#> [1] 2