Date objects and date formatting

as.Date(20,origin="1970-01-01")
[1] "1970-01-21"
d <- as.Date("1990-11-09")
format(d,"%e %B % Y")
[1] " 9 November % Y"
format(d,"%b %d, %y")
[1] "Nov 09, 90"
format(d,"%Y-%m-%d")
[1] "1990-11-09"
as.Date("11/09/90", format="%m/%d/%y")
[1] "1990-11-09"