计算函数中向量中的每个值

Question

I made a function which will calculate if a certain year is a leapyear which looks like this:

isLeapday<-function(x) {
     if (as.numeric(x)%%100==0 & as.numeric(x)%%400==0 | as.numeric(x)%%4==0 &      as.numeric(x)%%100!=0) return (TRUE) 
     else return (FALSE)
}


isLeapday(x)

I get the error message

"In if (as.numeric(x)%%100 == 0 & as.numeric(x)%%400 == 0 | as.numeric(x)%%4 == : the condition has length > 1 and only the first element will be used"

Basically only the first value is calculated, how do I make it so that it counts every value within the vector and if possible, returns a logical vector?

Answer 1

isLeapday<-function(x) {
  x %% 100 == 0 & x %% 400 == 0 | x %% 4 == 0 & x %% 100 != 0
}

years <- 2004:2013

isLeapday(years)

# [1]  TRUE FALSE FALSE FALSE  TRUE FALSE FALSE FALSE  TRUE FALSE

Or as mnel mentioned:

library("chron")
leap.year(years)

 [1]  TRUE FALSE FALSE FALSE  TRUE FALSE FALSE FALSE  TRUE FALSE

For the code of leap.year{chron} :

library("chron") 
edit(leap.year)

function (y) 
{
    if (inherits(y, "dates")) 
        y <- month.day.year(as.numeric(y), origin. = origin(y))$year
    y%%4 == 0 & (y%%100 != 0 | y%%400 == 0)
}