[R] Variable Argument Function

[Duncan Murdoch]

On 07/02/2016 6:12 PM, Robert Sherry wrote:
>
> I would like to write a function in R that would take a variable number
> of integers as parameters. I do not have a pressing reason to do this, I
> am just trying to learn R. I thought a good first step would be to print
> out the arguments. So I wrote the following function:
>
> f1 = function (...)
> {
>       list1 = as.list(...)

This is wrong.  The ... object is weird; it's not something that can be 
coerced to a list.  However, you can pass it as list(...) and it will 
give you what you were expecting.

The theory is that it will expand to multiple arguments to the list() 
function, which constructs a list containing them.  as.list() doesn't 
want a bunch of arguments, it will just ignore most of them.

Duncan Murdoch

>       for( i in 1:length(list1) )
>           cat( "i is ", list1[[i]], "\n" )
>       return (0)
> }
>
> I ran it as:
>       f1(2,4,10,12)
> and I get:
>       i is  2
>       [1] 0
> I was hoping for
>       i is  2
>       i is  4
>       i is  10
>       i is  12
>
> I am hoping somebody can tell me what I am doing wrong. Is using a list
> a bad idea?
>
> Thanks
> Bob
>
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