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) (defaults to 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  1970-07-07  52  52.45753         29
#> 2  1997-08-06  25  25.37534          2
#> 3  1933-06-01  89  89.55616         66
#> 4  1956-01-20  66  66.91781         43
#> 5  1937-05-20  85  85.58904         62
#> 6  1967-08-29  55  55.31233         32
#> 7  1989-05-15  33  33.60274         10
#> 8  1988-11-01  34  34.13699         11
#> 9  1931-08-12  91  91.35890         68
#> 10 1936-08-10  86  86.36438         63