change a column from birth date to age in r

Question

I am using data.table for the first time.

I have a column of about 400,000 ages in my table. I need to convert them from birth dates to ages.

What is the bes

Answer 1

Assume you have a data.table, you could do below:

library(data.table)
library(lubridate)
# toy data
X = data.table(birth=seq(from=as.Date("1970-01-01"), to=as.Date("1980-12-31"), by="year"))
Sys.Date()

Option 1 : use "as.period" from lubriate package

X[, age := as.period(Sys.Date() - birth)][]
         birth                   age
 1: 1970-01-01  44y 0m 327d 0H 0M 0S
 2: 1971-01-01  43y 0m 327d 6H 0M 0S
 3: 1972-01-01 42y 0m 327d 12H 0M 0S
 4: 1973-01-01 41y 0m 326d 18H 0M 0S
 5: 1974-01-01  40y 0m 327d 0H 0M 0S
 6: 1975-01-01  39y 0m 327d 6H 0M 0S
 7: 1976-01-01 38y 0m 327d 12H 0M 0S
 8: 1977-01-01 37y 0m 326d 18H 0M 0S
 9: 1978-01-01  36y 0m 327d 0H 0M 0S
10: 1979-01-01  35y 0m 327d 6H 0M 0S
11: 1980-01-01 34y 0m 327d 12H 0M 0S

Option 2 : if you do not like the format of Option 1, you could do below:

yr = duration(num = 1, units = "years")
X[, age := new_interval(birth, Sys.Date())/yr][]
# you get
         birth      age
 1: 1970-01-01 44.92603
 2: 1971-01-01 43.92603
 3: 1972-01-01 42.92603
 4: 1973-01-01 41.92329
 5: 1974-01-01 40.92329
 6: 1975-01-01 39.92329
 7: 1976-01-01 38.92329
 8: 1977-01-01 37.92055
 9: 1978-01-01 36.92055
10: 1979-01-01 35.92055
11: 1980-01-01 34.92055

Believe Option 2 should be the more desirable.