R/years.R

In yapomif: Yet another package of misc functions

years <- function(date=NULL) {

  if ( !(class(date)[1] %in% c("Date","POSIXct","POSIXlt")) )
    stop("Only Date, POSIXct and POSIXlt class dates")

  UseMethod("years")
 
}


years.Date <- function(date) {
    as.numeric(format(date, "%Y"))
}

years.POSIXct <- function(date) {
    as.numeric(format(date, "%Y"))
}

years.POSIXlt <- function(date) {
    date$year + 1900
}