Python Data Structures Ultimate Guide: Lists, Tuples, Dicts, and Sets Explained

Python Core Data Structures

A quick-reference guide to Lists, Tuples, Dictionaries, and Sets.

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List

Mutable Ordered Indexed

A dynamic, ordered collection of items that allows duplicate elements. Best for collections where order matters and items change frequently.

my_list = [1, "apple", 3.4, "apple"]
my_list.append("banana")

()

Tuple

Immutable Ordered Indexed

An immutable, ordered collection of items that allows duplicates. Faster than lists; ideal for fixed data and protecting data integrity.

my_tuple = (1, "apple", 3.4, "apple")
# my_tuple[0] = 2 (Raises TypeError)

{:}

Dictionary

Mutable Ordered (3.7+) Key-Mapped

A collection of key-value pairs. Keys must be unique and immutable, while values can be anything. Optimized for ultra-fast lookups.

my_dict = {"name": "Alice", "age": 30}
my_dict["email"] = "alice@dev.com"

{}

Set

Mutable Unordered Unique

An unordered collection of unique elements. Perfect for eliminating duplicate entries and performing mathematical set operations like unions.

my_set = {1, 2, 2, 3} # {1, 2, 3}
my_set.add(4)