Compute time between two date type string to get years in R [duplicate]

Question

This question already has answers here:

Get the difference between dates in terms of weeks, months, quarters, and years (10 answers)

Get date difference in years (floating point) (7 answers)

Closed 5 years ago.

d <-c("1948/05/28","1952/03/27","1994/12/09")
as.Date(d)
[1] "1948-05-28" "1952-03-27" "1994-12-09"
as.Date("2014-03-20")
[1] "2014-03-20"
as.Date("2014-03-20")-as.Date(d)
Time differences in days
[1] 24037 22638  7041
(as.Date("2014-03-20")-as.Date(d))/365
Time differences in days
[1] 65.85479 62.02192 19.29041

I use (as.Date("2014-03-20")-as.Date(d))/365 to get the years between them ,is there more formal way to do that?

Answer 1

Try this to ensure that it picks days as the unit. Also 365.25 is slightly better than 365 due to leap years:

as.numeric(difftime(as.Date("2014-03-20"), as.Date(d), unit = "days")) / 365.25

Answer 2

lubridate::as.interval() addresses exactly that.

Answer 3

This is a more efficient modification of G. Grothendieck's answer:

(as.integer(as.Date("2014-03-20")) - as.integer(as.Date(d))) / 365.25