Héctor Villalobos <hvillalo <at> ipn.mx> writes:
>
> Hi,
>
> I'm sure this one is very easy....
>
> I am trying to write a function where one of its arguments has two posible
> (strings) values,
> defaulting to one of them if none is specified. My problem is that when
> evaluating the function
> the following warning is produced:
>
> "the condition has length > 1 and only the first element will be used"
>
> I've read the help page of if() but I don't get it because when evaluating
> step by step the
> warning is not produced.
>
> Omitting the details of my function, below is an example of this
>
> ## Function
> fun <- function( n, result = c("simple", "complete") )
> {
> if ( is.null(result) )
> result <- "simple"
> if ( !(result %in% c("simple", "s", "complete", "c")) ) {
> stop("specify type of result 'simple' or 'complete'")
> } else {
> res <- rnorm(n)
> res
> }
> }
Take a look at ?match.arg for one solution.
fun <- function( n, result = c("simple", "complete") )
{
result <- match.arg(result)
res <- rnorm(n)
res
}
fun(n=20)
fun(n=20, result="simple")
fun(n=20, result="comp")
fun(n=20, result="something")
Mark Lyman
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