[R] passing elements of named vector / named list to function

[Jeff Newmiller]

It x is a list...

do.call(fun,x)

You should keep external data input away from this code construct to avoid intentional or unintentional misuse of your fun.

If your toy example were your actual usage I would suggest the collapse argument of paste.
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Sent from my phone. Please excuse my brevity.

On January 15, 2015 6:25:43 AM PST, Rainer M Krug <Rainer at krugs.de> wrote:
>
>Hi
>
>Following scenario: I have a function fun
>
>--8<---------------cut here---------------start------------->8---
>fun <- function(A, B, C, ...){paste(A, B, C, ...)}
>--8<---------------cut here---------------end--------------->8---
>
>and x defined as follow
>
>--8<---------------cut here---------------start------------->8---
>x <- 1:5
>names(x) <- LETTERS[x]
>--8<---------------cut here---------------end--------------->8---
>
>now I want to pass the *elements* of x to fun as named arguments, i.e.
>
>,----
>| > fun(A=1, B=2, C=3, D=4, E=5)
>| [1] "1 2 3 4 5"
>`----
>
>The below examples obviously do not work:
>
>,----
>| > fun(x)
>| Error in paste(A, B, C, list(...)) :
>|   argument "B" is missing, with no default
>| > fun(unlist(x))
>| Error in paste(A, B, C, list(...)) :
>|   argument "B" is missing, with no default
>`----
>
>How can I extract from x the elements and pass them on to fun()?
>
>I could easily change x to a list() if this would be easier.
>
>--8<---------------cut here---------------start------------->8---
>x <- list(A=1, B=2, C=3, D=4, E=5)
>--8<---------------cut here---------------end--------------->8---
>
>In my actual program, x can have different elements as well as fun -
>this is decided programmatically.
>
>Any suggestions how I can achieve this?
>
>Thanks,
>
>Rainer