Date-time must be a POSIXct, POSIXlt, Date, Period, chron, yearmon, yearqtr, zoo, zooreg, timeDate, xts, its, ti, jul, timeSeries, and fts objects. isoyear() returns years according to the ISO 8601 week calendar. epiyear() returns years according to the epidemilogical week calendars.

year(x)

year(x) <- value

isoyear(x)

epiyear(x)

Arguments

x

a date-time object

value

a numeric object

Value

the years element of x as a decimal number

Details

year does not yet support years before 0 C.E.

References

http://en.wikipedia.org/wiki/ISO_week_date http://www.cmmcp.org/epiweek.htm

Examples

x <- ymd("2012-03-26") year(x)
#> [1] 2012
year(x) <- 2001 year(x) > 1995
#> [1] TRUE