as.Date()，没有提到“起源”

Question

我刚开始用R编写代码，目的是避免if-else语句。我正在尝试寻找一个闰年，并编写了以下代码：

 leap <- function(year) {
 as.Date(year)
 return(
   gettextf("Year %Y is a leap year", ifelse(leap.year(year),year, "Year %Y is not a leap year"))
 )
}
leap(2019)

我明确地想要省略起始点，因为我想找出日历中的任何闰年。

另外，请告知这是否有效。

Answer 1

如果您不想指定原点，则需要向as.Date传递一个字符串。你的代码还有更多的问题。这是可行的：

library(lubridate)
leap <- function(year) {
  #don't forget to assign like this: 
  year <- year(as.Date(paste0(year, "-01-01"))) 
  
  #you need to nest your functions correctly:
  sprintf(ifelse(leap_year(year), 
                  "Year %d is a leap year", 
                  "Year %d is not a leap year"), 
           year)
 }

leap(c(2000:2020))
#[1] "Year 2000 is a leap year"     "Year 2001 is not a leap year" "Year 2002 is not a leap year"
 #[4] "Year 2003 is not a leap year" "Year 2004 is a leap year"     "Year 2005 is not a leap year"
#...