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  1950-06-04  73  73.38356         49
#> 2  1953-03-27  70  70.57260         46
#> 3  1968-11-29  54  54.89589         31
#> 4  1997-09-02  26  26.13699          2
#> 5  1981-09-03  42  42.13425         18
#> 6  1974-02-03  49  49.71507         25
#> 7  1947-03-27  76  76.57260         52
#> 8  1972-02-11  51  51.69315         27
#> 9  1959-12-06  63  63.87671         40
#> 10 1935-10-25  87  87.99178         64