Lists

Definition: Lists are ordered collections that can store multiple values in a single variable. They are one of the most versatile and frequently used data structures in Python.

Why: Lists are a main data structure topic because they allow you to manage groups of related data (like a list of usernames or prices) efficiently using a single name.

Syntax

list_name = [item1, item2, item3]

Example

fruits = ["apple", "banana", "mango"]
print(fruits)

# Accessing an item
print(fruits[0]) 

# Adding an item
fruits.append("orange")
print(fruits)

Explanation

• Square Brackets: Lists are defined using [ ].
• Indexing: Items are accessed by their position, starting at 0 (so fruits[0] is "apple").
• Append: The .append() method adds a new item to the very end of the list.

Useful List Features

• Change Values: You can update an item by referring to its index (e.g., fruits[1] = "cherry").
• Add Items: Use append() to add to the end or insert() to add at a specific spot.
• Remove Items: Use remove() to delete a specific value or pop() to remove an item at a certain index.
• Looping: You can use a for loop to process each item in the list one by one.

Key Notes

• Lists are mutable, meaning you can change, add, and remove items after the list has been created.
• A single list can hold different data types (e.g., a mix of strings, integers, and booleans).
• Lists maintain the order of items as they were inserted.