Hash Table Concept and Hash Functions in DSA Python - Build from Scratch

Hash Table Concept and Hash Functions

📖 Scenario: Imagine you are organizing a small library. You want to quickly find books by their titles. To do this, you decide to use a simple hash table where each book title is linked to its shelf number.

🎯 Goal: You will create a hash table using a Python dictionary, write a simple hash function to assign shelf numbers, and then store and display the books with their shelf numbers.

📋 What You'll Learn

Create a dictionary called books with given book titles as keys and empty values.

Create a simple hash function called simple_hash that takes a book title and returns a shelf number.

Use the hash function to assign shelf numbers to each book in the books dictionary.

Print the final books dictionary showing book titles and their shelf numbers.

💡 Why This Matters

🌍 Real World

Hash tables help organize data for quick searching, like finding books in a library by their titles.

💼 Career

Understanding hash tables and hash functions is important for software development, database indexing, and efficient data retrieval.

1

Create the initial books dictionary

Create a dictionary called books with these exact keys and empty values: 'Python Basics', 'Data Science', 'Machine Learning', 'Deep Learning', 'Artificial Intelligence'.

DSA Python

# Create the books dictionary with given titles and empty values
# Your code here

Hint

Use a dictionary with book titles as keys and null as values for now.

2

Define a simple hash function

Define a function called simple_hash that takes a parameter title. It should return the sum of the Unicode values of all characters in title modulo 10.

DSA Python

books = {
    'Python Basics': null,
    'Data Science': null,
    'Machine Learning': null,
    'Deep Learning': null,
    'Artificial Intelligence': null
}

# Define the simple_hash function below
# Your code here

Hint

Use ord() to get Unicode values and sum() to add them up. Use modulo 10 to limit shelf numbers.

3

Assign shelf numbers using the hash function

Use a for loop with variables title and _ to iterate over books.items(). Inside the loop, assign books[title] the value returned by simple_hash(title).

DSA Python

books = {
    'Python Basics': null,
    'Data Science': null,
    'Machine Learning': null,
    'Deep Learning': null,
    'Artificial Intelligence': null
}

def simple_hash(title):
    return sum(ord(char) for char in title) % 10

# Assign shelf numbers to each book using simple_hash
# Your code here

Hint

Use for title, _ in books.items(): to loop and assign shelf numbers.

4

Print the books dictionary with shelf numbers

Write print(books) to display the dictionary showing book titles and their assigned shelf numbers.

DSA Python

books = {
    'Python Basics': null,
    'Data Science': null,
    'Machine Learning': null,
    'Deep Learning': null,
    'Artificial Intelligence': null
}

def simple_hash(title):
    return sum(ord(char) for char in title) % 10

for title, _ in books.items():
    books[title] = simple_hash(title)

# Print the books dictionary
# Your code here

Hint

The printed dictionary shows each book title with its shelf number.