Given function and test vector:
multiply_stuff <- function(...) {
arguments <- list(...)
Reduce(f = `*`, x = arguments)
}
test_vec <- c(1, 20, 3, 40, 5, 60)
I would like to create an unevaluated call
automatically listing all arguments of the passed vector. In this example that would be equivalent of expression:
call("multiply_stuff",
test_vec[1],
test_vec[2],
test_vec[3],
test_vec[4],
test_vec[5],
test_vec[6])
For instance for the vector:
test_vec_B <- c(1, 5, 6, 8, 9, 11, 12, 14, 20, 11)
I would like to automatically list all test_vec_B
arguments within call("multiply_stuff",...)
. Naturally this won't work:
call("multiply_stuff", test_vec_B)
call("multiply_stuff", list(test_vec_B))
Unevaluated expression equivalent to:
call(
"multiply_stuff",
test_vec_B[1],
test_vec_B[2],
test_vec_B[3],
test_vec_B[4],
test_vec_B[5],
test_vec_B[6],
test_vec_B[7],
test_vec_B[8],
test_vec_B[9],
test_vec_B[10]
)
You can create a call
object and then add arguments to it:
multiply_stuff <- function(...) {
arguments <- list(...)
Reduce(f = `*`, x = arguments)
}
test_vec_B <- c(1, 5, 6, 8, 9, 11, 12, 14, 20, 11)
get_call <- function(f, arg_vector){
my_call <- call(f)
my_call[2:(length(arg_vector) + 1)] <- arg_vector
return(my_call)
}
multiply_stuff(1, 5, 6, 8, 9, 11, 12, 14, 20, 11)
[1] 878169600
test_call <- get_call("multiply_stuff", test_vec_B)
eval(test_call)
[1] 878169600
Explanation: when you create a call
object, you can access/modify the function and its arguments by index just like usual. Index 1 is the function call, indices from 2 onwards are arguments.Run to verify:
test_call2 <- call("sum", 1, 2)
test_call2[1]
test_call2[2]
test_call2[3]
eval(test_call2)
test_call2[3] <- 1234
eval(test_call2)