Converting dates before January 1, 1970 in R

Question

I am trying to convert a column of dates into Date objects in R, but I can\'t seem to get the desired results. These individuals have birth dates before January 1, 1970, so when

Answer 1

No need for add-on packages, base R is fine. But you need to specify the century:

R> as.Date("1954-01-12")
[1] "1954-01-12"
R> 

If you need non-default formats, just specify them:

R> as.Date("19540112", "%Y%m%d")
[1] "1954-01-12"
R> 

Edit: In case your data really comes in using the %y% format, and you happen to make the policy decision that the 19th century is needed , here is one base R way of doing it:

R> d <- as.Date("540112", "%y%m%d")
R> dlt <- as.POSIXlt(d)
R> dlt$year <- dlt$year - 100
R> as.Date(dlt)
[1] "1954-01-12"
R>