HashMaps in Action: Solving Real-World Problems in Python

Hello there! In this lesson we will apply HashMaps, a data structure, to real-world challenges. Our focus will be on solving tasks such as cataloging books in a library, counting votes in an election, and tracking inventories.

HashMaps are beneficial in real-life applications, such as the ones mentioned above, due to their ability to rapidly retrieve data with unique keys and efficiently handle larger datasets. Let's understand their efficiency with some actual examples.

Suppose you're asked to manage the cataloging of books in a library. In Python, we represent HashMaps using dictionaries. Here, the book ID serves as the key, while the details of the book, such as the title, author, and year of publication, are stored as values.

This approach allows us to add, search for, and remove books from our library catalog using just a few lines of Python code.

library_catalog = {}  # Initializing HashMap

# Details of a book
book_id = "123"
book_details = {"title": "To Kill a Mockingbird", "author": "Harper Lee", "year_published": 1960}

library_catalog[book_id] = book_details  # Adding a book to library catalog

if book_id in library_catalog:  # Searching for a book
    print(library_catalog[book_id])
    
del library_catalog[book_id]  # Removing a book from library

As you can see, HashMaps make the task of cataloging books in the library simpler and more efficient!

Imagine a scenario in which we need to count votes in an election. We employ a HashMap, where each name is a unique key, and the frequency of that name serves as the associated value. Let's write some Python code to better understand this.

votes_list = ["Alice", "Bob", "Alice", "Charlie", "Bob", "Alice"]  # Cast votes
vote_counts = {}  # Initializing a HashMap

# Counting the votes
for name in votes_list:
    if name in vote_counts:  # If name is already a key
        vote_counts[name] += 1  # increment its value (count)
    else:  # If name doesn't exist as a key
        vote_counts[name] = 1 # add it as a key and set value as 1

print(vote_counts)
# Prints {'Alice': 3, 'Bob': 2, 'Charlie': 1}

HashMaps facilitate the efficient counting of votes.