Prof. Riley has already answered this but I thought I would add a bit more detail.
# define a function chron.year.expand.0 with a different cutoff. # You can choose other cutoffs too but here we have chosen 0. chron.year.expand.0 <- function(x) year.expand(x,cut=0)
# run chron -- we have not yet set the new year expansion
chron("01/02/29", out.format="year-month-day")
[1] 2029-January-02
# change the year expansion option to point to the new function
options(chron.year.expand = "chron.year.expand.0")
chron("01/02/29", out.format="year-month-day")
[1] 1929-January-02
# now change it back
options(chron.year.expand = "year.expand")
chron("01/02/29", out.format="year-month-day")
[1] 2029-January-02 Date: Wed, 28 Jan 2004 11:50:11 +0100 From: Massimiliano Tripoli <tripoli at med.unibs.it> To: <R-help at stat.math.ethz.ch> Subject: [R] Julian dates Hi all, I have problems with years of dates using "chron" package. I don't understand why R by this istruction:
dates("01/02/29",out.format="d/m/year")
[1] 02/Jan/2029
dates("01/02/30",out.format="d/m/year")
[1] 02/Jan/1930 reads "29" as 2029 and "30" as 1930. How could I change to read "00" to "05" like 2000 to 2005 and "06" to "99" like 1906 to 1999 ? Thank you Massimiliano