Passing arbitrary arguments to multiple nested functions in R

Question

Can't find a question similar to what I am trying to do. I have a workhorse function that can take any of a class of custom-made sub-functions, with their respective arguments, and do certain processing on it, like the following toy examples:

func1 <- function(a, b, c) {a + b * c}

func2 <- function(x, y, z, bob, bleb) {(x / y)^bleb * z/bob}

workhorse <- function(m, n, o, FUN, ...) {
  result <- FUN(x, y, ...)
  [process result with m, n, and o]
}

By itself, this works perfectly well as intended, as in

foo <- workhorse(m, n, o, func1, a, b, c)
foo2 <- workhorse(m, n, o, func2, x, y, z, bob, bleb)

I am trying to create a wrapper for workhorse (meta_workhorse) that will accept a list of functions (by quoted name) to run through workhorse and combine the results, something like below.

FUN_list <- c('func1', 'func2')
ARGS_list <- list(c(a, b, c), c(x, y, z, bob, bleb))

meta_workhorse <- function(mm, nn, oo, FUN_list, ARGS_list) {
  meta_result <- sapply(1:length(FUN_list), function(x) {
    workhorse(mm, nn, oo, get(FUN_list[x]), ARGS_list[x], ...)
  }
}

The problem is that each of the sub-functions take different arguments, so I need to link the function name going into the get() function with the corresponding list of arguments in ARGS_list. I've tried everything I could think of, including do.calls, setting formals(workhorse), to no avail. How do I pass the arguments in this case?

EDIT: Nicola's answer solved most of the issue, but still have one subfuction (using a packaged function) keeps giving the error "unused argument ... = list(x, y)". Looking for some suggestions while I dig through previous ellipsis questions.

nicola nicola · Accepted Answer · 2014-10-12T22:17:27

I guess you should declare your ARGS_list as a list of lists, instead of a normal list. Then, you can proceed to use do.call. An example (hoping that is what you are looking for):

   func1 <- function(a, b, c) {a + b * c}
   func2 <- function(x, y, z, bob, bleb) {(x / y)^bleb * z/bob}
   workhorse <- function(m, n, o, FUN, ...) {
     result <- FUN(...)
     result+m+n*o
   }
   FUN_list <- c('func1', 'func2')    
   ARGS_list <- list(list(a=1, b=2, c=3), list(x=4, y=5, z=6, bob=7, bleb=8))
   meta_workhorse <- function(mm, nn, oo, FUN_list, ARGS_list) {
      sapply(1:length(FUN_list), function(x) {
        do.call(workhorse,c(list(m=mm,n=nn,o=oo,FUN=get(FUN_list[x])),ARGS_list[[x]]))
      })
   }

   meta_workhorse(1,2,3,FUN_list,ARGS_list)
   # [1] 14.000000  7.143805

Passing arbitrary arguments to multiple nested functions in R

1 Answers