Default argument values in R Programming - Mini Project: Build & Apply

Default argument values

📖 Scenario: Imagine you are creating a simple calculator function in R that adds two numbers. Sometimes, you want to add a number to zero by default if the second number is not given.

🎯 Goal: Build a function called add_numbers that adds two numbers, where the second number has a default value of 0.

📋 What You'll Learn

Create a function named add_numbers with two parameters: a and b

Set the default value of parameter b to 0

Return the sum of a and b

Call the function with one argument and print the result

Call the function with two arguments and print the result

💡 Why This Matters

🌍 Real World

Default argument values are useful in many programs where some inputs are optional or have common defaults, like setting a default tax rate or default color.

💼 Career

Understanding default arguments helps you write flexible and user-friendly functions, a key skill for software development and data analysis.

1

Create the function skeleton

Write a function named add_numbers with two parameters: a and b. Do not set any default values yet.

R Programming

add_numbers <- function(a, b) {
  # Your code here
}

Need a hint?

Use the function keyword to create a function with parameters a and b.

2

Set default value for second parameter

Modify the function add_numbers so that the parameter b has a default value of 0.

R Programming

add_numbers <- function(a, b = 0) {
  # Your code here
}

Need a hint?

Set the default value by using b = 0 inside the function parameters.

3

Add the core logic to sum the numbers

Inside the function add_numbers, return the sum of a and b.

R Programming

add_numbers <- function(a, b = 0) {
  return(a + b)  # Your code here
}

Need a hint?

Use return(a + b) to send back the sum.

4

Test the function with one and two arguments

Call the function add_numbers with one argument 5 and print the result. Then call it with two arguments 5 and 3 and print the result.

R Programming

print(add_numbers(5))  # Your code here
print(add_numbers(5, 3))  # Your code here

Need a hint?

Use print(add_numbers(5)) and print(add_numbers(5, 3)) to show the results.