Reading Dates with two digit years in R

Question

I am trying to parse a date with 2 digit years. However this does not work. Can somebody please tell me why?

Browse[1]> as.Date("Jan-84", format = "%b-%y")
[1] NA

Answer 1

The zoo package is helpful for this:

require(zoo)

x <- as.yearmon("Jan-84", format = "%b-%y")

The lines above first convert the input to class yearmon:

"Jan 1984"

From there you can convert the yearmon class to Date (or POSIXct), like this:

x <– as.Date(x)

Now the object is of class Date:

"1984-01-01"