Array comparison and set operations in Ruby - Mini Project: Build & Apply

Array comparison and set operations

📖 Scenario: You are managing two lists of attendees for two different events. You want to find out who attended both events, who attended only one, and who attended either event.

🎯 Goal: Build a Ruby program that compares two arrays of names using set operations to find common attendees, unique attendees, and all attendees combined.

📋 What You'll Learn

Create two arrays with exact names as given

Create a variable to hold the common attendees

Create a variable to hold attendees unique to the first event

Create a variable to hold all attendees from both events

Print the results exactly as specified

💡 Why This Matters

🌍 Real World

Comparing lists of participants, customers, or items is common in event planning, marketing, and inventory management.

💼 Career

Understanding array comparison and set operations helps in data analysis, filtering, and reporting tasks in many programming jobs.

1

Create two arrays of attendees

Create an array called event1_attendees with these exact names: "Alice", "Bob", "Charlie". Also create an array called event2_attendees with these exact names: "Bob", "Diana", "Edward".

Ruby

# Create the arrays event1_attendees and event2_attendees with the exact names
# Your code here

Need a hint?

Use square brackets [] to create arrays and separate names with commas.

2

Create variables for set operations

Create a variable called common_attendees that holds the names present in both event1_attendees and event2_attendees. Create a variable called unique_to_event1 that holds names in event1_attendees but not in event2_attendees. Create a variable called all_attendees that holds all unique names from both arrays combined.

Ruby

event1_attendees = ["Alice", "Bob", "Charlie"]
event2_attendees = ["Bob", "Diana", "Edward"]
# Create common_attendees, unique_to_event1, and all_attendees variables using set operations
# Your code here

Need a hint?

Use & for intersection, - for difference, and | for union of arrays.

3

Prepare output strings

Create a variable called common_str that joins the names in common_attendees with commas. Create a variable called unique_str that joins the names in unique_to_event1 with commas. Create a variable called all_str that joins the names in all_attendees with commas.

Ruby

event1_attendees = ["Alice", "Bob", "Charlie"]
event2_attendees = ["Bob", "Diana", "Edward"]

common_attendees = event1_attendees & event2_attendees
unique_to_event1 = event1_attendees - event2_attendees
all_attendees = event1_attendees | event2_attendees
# Create common_str, unique_str, and all_str by joining array elements with commas
# Your code here

Need a hint?

Use the join method with ", " to combine array elements into a string.

4

Print the results

Print the following lines exactly using puts:
1. "Common attendees: " followed by common_str
2. "Unique to event 1: " followed by unique_str
3. "All attendees: " followed by all_str

Ruby

event1_attendees = ["Alice", "Bob", "Charlie"]
event2_attendees = ["Bob", "Diana", "Edward"]

common_attendees = event1_attendees & event2_attendees
unique_to_event1 = event1_attendees - event2_attendees
all_attendees = event1_attendees | event2_attendees

common_str = common_attendees.join(", ")
unique_str = unique_to_event1.join(", ")
all_str = all_attendees.join(", ")
# Print the results as specified
# Your code here

Need a hint?

Use puts and string interpolation with #{} to print variables inside strings.