R functions: passing arguments with ellipsis

Question

I have a question regarding base R usage. It might be asked before, however I wasn't able to find solution to my problem.

I have a function that calls another function. Arguments to second function are passed using ellipsis (

...

). However, I get error message:

object "OBJECT" not found

.

f1 <- function(a, ...) {

    print(a)

    f2(...)

}

f2 <- function(...) {

    print(b == TRUE)

    print(runif(c))

}

f1(2, b = FALSE, c = 2)

Which gives me:

Error in print(b == TRUE) : object 'b' not found

.

I know that it is possible to get around this problem using

args <- list(...)

and then calling each argument separately, but I imagine that this gets complicated when having lots of arguments (not only two).

Question

How to pass arguments from

f1

to

f2

using ellipsis?

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Answer 1

So the ellipses are used to save you specifying all the arguments of f2 in the arguments of f1. Though when you declare f2, you still have to treat it like a normal function, so specify the arguments b and c.

f1 <- function(a, ...) {
    print(a)
    f2(...)
}

# Treat f2 as a stand-alone function
f2 <- function(b, c) {
    print(b == TRUE)
    print(runif(c))
}

f1(2, b=FALSE, c=2)

[1] 2
[1] FALSE
[1] 0.351295 0.9384728

R functions: passing arguments with ellipsis

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