Lists in Python

Lists are one of the most powerful and versatile data structures in Python. A list is an ordered, mutable collection of items.

Creating Lists

You can create lists by placing items inside square brackets [], separated by commas.

# List of integers
numbers = [1, 2, 3, 4, 5]

# List of mixed data types
mixed = [1, "Python", 3.14, True]

# Empty list
empty = []

Accessing Elements

Each item in a list has an index, starting from 0.

fruits = ["apple", "banana", "cherry"]
print(fruits[0])  # Output: apple
print(fruits[-1]) # Output: cherry (last item)

List Slicing

Like strings, lists can be sliced to get a sub-list.

numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
print(numbers[2:5])   # Output: [2, 3, 4]
print(numbers[:4])    # Output: [0, 1, 2, 3]
print(numbers[::2])   # Output: [0, 2, 4, 6, 8] (step of 2)

Common List Methods

Python provides several methods for modifying lists.

Method	Description
append(item)	Adds an item to the end of the list
insert(index, item)	Inserts an item at a specific index
remove(item)	Removes the first occurrence of an item
pop(index)	Removes and returns the item at the given index (default is last)
sort()	Sorts the list in place
reverse()	Reverses the order of the list in place

list = [3, 1, 4]
list.append(2)
list.sort()
print(list) # Output: [1, 2, 3, 4]

List Comprehensions

List comprehensions provide a concise way to create lists.

# Create a list of squares
squares = [x**2 for x in range(10)]
print(squares) # Output: [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]