Data Structures in Python - Episode 5: Dictionaries

Data Structures in Python - Episode 5: Dictionaries

Introduction

Dictionaries are key-value pairs used to store and retrieve data efficiently. They are unordered collections, where each key must be unique and immutable.

Example 1: Creating a Dictionary

# Creating a dictionary
my_dict = {"name": "Alice", "age": 25, "city": "New York"}
print(my_dict)

{'name': 'Alice', 'age': 25, 'city': 'New York'}

Example 2: Accessing and Modifying Data

# Accessing a value
print(my_dict["name"])

# Modifying a value
my_dict["age"] = 26
print(my_dict)

Alice
{'name': 'Alice', 'age': 26, 'city': 'New York'}

Example 3: Useful Dictionary Methods

# Some common methods
print(my_dict.keys())
print(my_dict.values())
print(my_dict.items())

dict_keys(['name', 'age', 'city'])
dict_values(['Alice', 26, 'New York'])
dict_items([('name', 'Alice'), ('age', 26), ('city', 'New York')])

Quick Recap

Operation	Description
dict[key]	Access the value associated with a key
dict.keys()	Returns all keys
dict.values()	Returns all values
dict.items()	Returns all key-value pairs

Important Notes

Tip: Keys must be unique and immutable (e.g., strings, numbers, tuples).
Warning: Attempting to access a non-existent key will raise a KeyError.