Passing arguments in R within functions, error unused arguments

Question

Consider the first function:

fruits <- function(apples, oranges){
   apples + oranges
}

#example#
> fruits(2,3) 
[1] 5

The second function uses the first function fruits:

fruitsandvegetables <- function(tomatoes){
   fruits(apples, oranges) + tomatoes
}

Now consider the following errors:

> fruitsandvegetables(3)
  Error in fruits(apples, oranges) : object 'apples' not found
> fruitsandvegetables(3, apples = 2, oranges = 3)
  Error in fruitsandvegetables(3, apples = 2, oranges = 3) : 
  unused arguments (apples = 2, oranges = 3)
> fruitsandvegetables(tomatoes = 3, apples = 2, oranges = 3)
  Error in fruitsandvegetables(tomatoes = 3, apples = 2, oranges = 3) : 
  unused arguments (apples = 2, oranges = 3)

I understand these errors, but I was wondering if there is a simple way to get around this. For more complex function with many arguments, rewriting the functions can be very tedious.

In otherwords I would like the function to behave this way:

fruitsandvegetables(3, apples = 2, oranges =3)
[8]

fruitsandvegetables function should be fruitsandvegetables <- function(tomatoes, apples, oranges){ fruits(apples, oranges) + tomatoes } — Ronak Shah
– Ronak Shah, Commented Oct 25, 2016 at 6:11

baptiste · Accepted Answer · 2016-10-25 08:27:42Z

4

try this,

fruitsandvegetables <- function(tomatoes, ...){
  fruits(...) + tomatoes
}

Note: problems may arise if a tomato turns out to be a fruit

edited Oct 25, 2016 at 8:27

answered Oct 25, 2016 at 7:19

baptiste

77.3k21 gold badges207 silver badges301 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Chrisss Over a year ago

I think the use of ... is far more elegant and flexible than using missing or making sure all nested functions share the same argument names as their higher/lower level functions

Ronak Shah · Accepted Answer · 2016-10-25 10:42:31Z

0

There is no way fruitsandvegetables function comes to know what is apples and oranges.

You may include these two parameters as argument to the function like ,

fruitsandvegetables <- function(tomatoes, apples, oranges) {
     fruits(apples, oranges) + tomatoes 
}

fruitsandvegetables(3, apples = 2,oranges = 3)
#[1] 8

Moreover,

fruitsandvegetables(3,2,3)
#[1] 8

answered Oct 25, 2016 at 10:42

Ronak Shah

391k20 gold badges173 silver badges237 bronze badges

Collectives™ on Stack Overflow

Passing arguments in R within functions, error unused arguments

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related