Function arguments in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a function that takes one argument and returns it.

R Programming

my_function <- function([1]) {
  return([1])
}

Drag options to blanks, or click blank then click option'

Ax

By

Cz

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for the argument and return value.

Leaving the argument blank.

The argument name x is used consistently in the function definition and return statement.

2fill in blank

medium

Complete the code to call the function with the argument 5.

R Programming

result <- my_function([1])
print(result)

Drag options to blanks, or click blank then click option'

A"5"

Bx

C5

Dmy_function

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a string instead of a number.

Passing the function name instead of an argument.

The function should be called with the number 5, not a string or variable name.

3fill in blank

hard

Fix the error in the function definition to correctly set a default argument value of 10.

R Programming

my_function <- function(x = [1]) {
  return(x)
}

Drag options to blanks, or click blank then click option'

A10

Bten

C"10"

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string instead of a number for the default value.

Using a variable name that is not defined.

The default value should be the number 10 without quotes.

4fill in blank

hard

Fill both blanks to define a function with two arguments where the second has a default value.

R Programming

my_function <- function([1], [2] = 5) {
  return([1] + [2])
}

Drag options to blanks, or click blank then click option'

Ax

By

Cz

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same name for both arguments.

Not providing a default value for the second argument.

The function uses x and y as argument names, with y having a default value.

5fill in blank

hard

Fill all three blanks to create a function that multiplies two arguments and adds a third with a default value.

R Programming

my_function <- function([1], [2], [3] = 1) {
  return([1] * [2] + [3])
}

Drag options to blanks, or click blank then click option'

Aa

Bb

Cc

Dd

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same name for multiple arguments.

Not setting a default value for the third argument.

The function uses a, b, and c as argument names, with c having a default value.

Practice

1. What is the purpose of function arguments in R?
my_function <- function(x, y) { x + y }

easy

A. To create variables outside the function

B. To print output from the function

C. To send information into the function for processing

D. To stop the function from running

Solution

1. Step 1: Understand what arguments do

   Arguments are values you give to a function so it can use them inside its code.

2. Step 2: Look at the example function

   The function takes x and y as inputs and adds them, showing arguments are inputs.

3. Final Answer:

   To send information into the function for processing -> Option C

4. Quick Check:

   Function arguments = inputs [OK]

Hint: Arguments are inputs you give to functions [OK]

Common Mistakes:

• Thinking arguments print output
• Confusing arguments with variables outside
• Believing arguments stop function execution

2. Which of the following is the correct way to define a function with two arguments a and b in R?

easy

A. my_func <- function {a, b} return(a + b)

B. my_func <- function(a, b) { return(a + b) }

C. my_func <- function[a, b] { return(a + b) }

D. my_func <- function(a; b) { return(a + b) }

Solution

1. Step 1: Recall R function syntax

   Functions use parentheses () to list arguments separated by commas.

2. Step 2: Check each option

   Only my_func <- function(a, b) { return(a + b) } uses parentheses and commas correctly; others use wrong brackets or separators.

3. Final Answer:

   my_func <- function(a, b) { return(a + b) } -> Option B

4. Quick Check:

   Function args use (a, b) [OK]

Hint: Use parentheses and commas for arguments [OK]

Common Mistakes:

• Using square brackets instead of parentheses
• Separating arguments with semicolons
• Omitting parentheses around arguments

3. What will be the output of this R code?

add <- function(x, y = 5) {
  x + y
}
add(3)

medium

A. 8

B. 3

C. 5

D. Error: missing argument y

Solution

1. Step 1: Understand default argument values

   The function add has y defaulting to 5 if not provided.

2. Step 2: Call the function with one argument

   Calling add(3) uses x=3 and default y=5, so result is 3 + 5 = 8.

3. Final Answer:

   8 -> Option A

4. Quick Check:

   3 + default 5 = 8 [OK]

Hint: Default arguments fill in missing values [OK]

Common Mistakes:

• Expecting error when argument is missing
• Ignoring default argument values
• Confusing which argument has default

4. Identify the error in this R function definition:

multiply <- function(x, y) {
  result <- x * z
  return(result)
}

medium

A. Function should not use return statement

B. Function name cannot be multiply

C. Arguments must have default values

D. Variable z is not defined inside the function

Solution

1. Step 1: Check variables used inside function

   The function uses z but only x and y are arguments; z is undefined.

2. Step 2: Understand variable scope

   Variables inside functions must be defined or passed as arguments; z is missing.

3. Final Answer:

   Variable z is not defined inside the function -> Option D

4. Quick Check:

   Undefined variable = error [OK]

Hint: Use only defined arguments or variables inside functions [OK]

Common Mistakes:

• Using variables not passed as arguments
• Thinking return is optional error
• Believing arguments must have defaults

5. You want to create a function greet that takes a name and an optional greeting message (default "Hello"). Which function definition is correct to achieve this?

hard

A. greet <- function(name, message = "Hello") { paste(message, name) }

B. greet <- function(name = "Hello", message) { paste(message, name) }

C. greet <- function(name, message) { paste(message, name) }

D. greet <- function(message = "Hello", name) { paste(name, message) }

Solution

1. Step 1: Identify default argument placement

   In R, arguments with defaults must come after those without defaults.

2. Step 2: Check each option

   greet <- function(name, message = "Hello") { paste(message, name) } correctly places message with default after name without default and uses paste correctly.

3. Final Answer:

   greet <- function(name, message = "Hello") { paste(message, name) } -> Option A

4. Quick Check:

   Default args last = correct [OK]

Hint: Put default arguments after required ones [OK]

Common Mistakes:

• Placing default arguments before required ones
• Forgetting default values
• Mixing argument order in paste function