[R] coping with a warning in if()

[jim holtman]

Look at what happens when you don't pass in 'result':

> c('simple', 'complete') %in% c("simple", "s", "complete", "c")
[1] TRUE TRUE

result is a vector of length two and provides two results and the 'if'
was only expecting one.  You might have to debug your code some more.

You probably want to use 'missing' and not 'is.null'

2010/1/19 Héctor Villalobos <hvillalo at ipn.mx>:
> 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
>  }
> }
>
> ## This gives the warning
> fun(n=20)
>
> ## But this not
> fun(n=20, result="other")
>
> ## The warning is not produced when doing this step by step
>  n <- 20
>  result <-  "simple"
>  if ( !(result %in% c("simple", "s", "complete", "c")) ){
>      stop("specify type of result 'simple' or 'complete'")
>  } else {
>  res <- rnorm(n)
>  res
>  }
>
> ## or here
>  n <- 20
>  result <-  "other"
>  if ( !(result %in% c("simple", "s", "complete", "c")) ){
>      stop("specify type of result 'simple' or 'complete'")
>  } else {
>  res <- rnorm(n)
>  res
>  }
>
>
> Thanks for your time
>
> Héctor
>
>
> --
> Héctor Villalobos <hvillalo at ipn.mx>
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>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?