Recursive functions in R Programming - Mini Project: Build & Apply

Understanding Recursive Functions in R

📖 Scenario: Imagine you want to calculate the factorial of a number. Factorial means multiplying a number by all the numbers below it down to 1. For example, 5 factorial (written as 5!) is 5 x 4 x 3 x 2 x 1 = 120.We will learn how to write a recursive function in R to calculate factorials. Recursive means the function calls itself with a smaller number until it reaches 1.

🎯 Goal: Build a recursive function in R called factorial that calculates the factorial of a given number.

📋 What You'll Learn

Create a variable with a number to calculate factorial for

Create a base case variable to stop recursion

Write a recursive function named factorial that calls itself

Print the factorial result

💡 Why This Matters

🌍 Real World

Recursive functions are useful in many areas like calculating factorials, navigating file systems, or solving puzzles like the Tower of Hanoi.

💼 Career

Understanding recursion helps in programming jobs that require problem-solving skills and working with algorithms, especially in software development and data science.

1

Create a variable with the number to calculate factorial

Create a variable called num and set it to 5.

R Programming

# Create a variable called num and set it to 5
# Your code here

Need a hint?

Use the assignment operator <- to set num to 5.

2

Create a base case variable for recursion

Create a variable called base_case and set it to 1 to stop the recursion when the number reaches 1.

R Programming

num <- 5
# Create a variable called base_case and set it to 1
# Your code here

Need a hint?

The base case is the smallest number where recursion stops. For factorial, it is 1.

3

Write the recursive factorial function

Write a function called factorial that takes a parameter n. If n equals base_case, return 1. Otherwise, return n multiplied by factorial(n - 1).

R Programming

num <- 5
base_case <- 1
# Write the recursive factorial function here
# Your code here

Need a hint?

Use an if statement to check if n is the base case. Use recursion by calling factorial(n - 1).

4

Print the factorial of the number

Use print() to display the result of factorial(num).

R Programming

num <- 5
base_case <- 1
factorial <- function(n) {
  if (n == base_case) {
    return(1)
  } else {
    return(n * factorial(n - 1))
  }
}
# Print the factorial of num
# Your code here

Need a hint?

Call factorial(num) inside print() to show the result.