Age in Years of Individuals

Calculates age in years based on a reference date, which is the system date at default.

Usage

age(x, reference = Sys.Date(), exact = FALSE, na.rm = FALSE, ...)

Arguments

x

date(s), character (vectors) will be coerced with as.POSIXlt()

reference

reference date(s) (default is today), character (vectors) will be coerced with as.POSIXlt()

exact

a logical to indicate whether age calculation should be exact, i.e. with decimals. It divides the number of days of year-to-date (YTD) of x by the number of days in the year of reference (either 365 or 366).

na.rm

a logical to indicate whether missing values should be removed

...

arguments passed on to as.POSIXlt(), such as origin

Value

An integer (no decimals) if exact = FALSE, a double (with decimals) otherwise

Details

Ages below 0 will be returned as NA with a warning. Ages above 120 will only give a warning.

This function vectorises over both x and reference, meaning that either can have a length of 1 while the other argument has a larger length.

See also

To split ages into groups, use the age_groups() function.

Examples

# 10 random pre-Y2K birth dates
df <- data.frame(birth_date = as.Date("2000-01-01") - runif(10) * 25000)

# add ages
df$age <- age(df$birth_date)

# add exact ages
df$age_exact <- age(df$birth_date, exact = TRUE)

# add age at millenium switch
df$age_at_y2k <- age(df$birth_date, "2000-01-01")

df
#>    birth_date age age_exact age_at_y2k
#> 1  1974-04-24  48  48.88767         25
#> 2  1976-01-15  47  47.15890         23
#> 3  1971-07-03  51  51.69589         28
#> 4  1939-11-17  83  83.32055         60
#> 5  1937-04-17  85  85.90685         62
#> 6  1934-11-28  88  88.29041         65
#> 7  1944-07-14  78  78.66575         55
#> 8  1992-04-05  30  30.93973          7
#> 9  1936-06-15  86  86.74521         63
#> 10 1998-02-23  25  25.05205          1