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.

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  1999-06-30  26  26.69589          0
#> 2  1968-01-29  58  58.11233         31
#> 3  1965-12-05  60  60.26301         34
#> 4  1980-03-01  46  46.02740         19
#> 5  1949-11-01  76  76.35616         50
#> 6  1947-02-14  79  79.06849         52
#> 7  1940-02-19  86  86.05479         59
#> 8  1988-01-10  38  38.16438         11
#> 9  1997-08-27  28  28.53699          2
#> 10 1978-01-26  48  48.12055         21

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