Function arguments in R Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of function with default and named arguments

What is the output of this R code?

R Programming

f <- function(x, y = 2) {
  x + y
}

result <- f(y = 3, x = 4)
print(result)

A Error: unused argument (y = 3)

B [1] 5

C [1] 7

D [1] 6

💡 Hint

Remember that named arguments can be passed in any order.

The function f adds x and y. The call f(y=3, x=4) assigns x=4 and y=3, so the result is 4 + 3 = 7. But the default y=2 is overridden by y=3. The sum is 7.

❓ Predict Output

intermediate

Effect of missing argument with default

What will this R code print?

R Programming

g <- function(a, b = 10) {
  a * b
}

print(g(5))

A [1] 50

B Error: argument "b" is missing, with no default

C [1] 15

D [1] 5

💡 Hint

Check the default value of b.

The function multiplies a by b. Since b has a default value of 10 and is not provided, it uses 10. So 5 * 10 = 50.

🔧 Debug

advanced

Identify the error in function argument usage

What error does this R code produce?

R Programming

h <- function(x, y) {
  x + y
}

h(3)

A Error in h(3) : unused argument (3)

B Error in h(3) : argument "y" is missing, with no default

C Error in h(3) : object 'y' not found

D No error, output is 3

💡 Hint

Check if all required arguments are provided.

The function h requires two arguments x and y. Calling h(3) provides only x, so R raises an error about missing argument y.

❓ Predict Output

advanced

Output with ... (ellipsis) argument

What does this R code print?

R Programming

k <- function(x, ...) {
  args <- list(...)
  sum <- x
  for (val in args) {
    sum <- sum + val
  }
  sum
}

print(k(1, 2, 3, 4))

A [1] 10

B [1] 24

C [1] 1

D Error: object 'val' not found

💡 Hint

The ... collects extra arguments as a list.

The function sums x plus all values passed in ... . Here, x=1 and ... = 2,3,4. Sum is 1+2+3+4=10.

🧠 Conceptual

expert

Number of arguments in a function call

How many arguments are passed to the function call below?

R Programming

m <- function(a, b = 2, c = 3) {
  a + b + c
}

m(1, c = 4)

A Error: missing argument

B 3

C 1

D 2

💡 Hint

Count only arguments explicitly passed in the call.

The call m(1, c=4) passes two arguments: a=1 (positional) and c=4 (named). b uses default 2. So 2 arguments are passed.