Python Lists and Dictionaries

Introduction

Lists and dictionaries are two of Python's most used data structures. Mastering them is essential for writing effective Python code.

Lists

A list is an ordered collection of items.

fruits = ["apple", "banana", "cherry"]

print(fruits[0]) # apple

Common List Operations

You can add, remove, and loop over items easily.

fruits.append("mango")

fruits.remove("banana")

for fruit in fruits:

print(fruit)

List Comprehensions

A concise way to create lists.

squares = [x * x for x in range(10)]

Dictionaries

A dictionary stores key-value pairs.

person = {

"name": "Alice",

"age": 25,

"city": "New York"

}

print(person["name"]) # Alice

Looping Over Dictionaries

Use .items() to get both key and value.

for key, value in person.items():

print(key, ":", value)

Nested Structures

You can combine lists and dictionaries for complex data.

users = [

{"name": "Alice", "age": 25},

{"name": "Bob", "age": 30}

]