Python Mastery – From Basics to Brilliance / Data Structures in Python

List vs Tuple vs Set vs Dictionary

🔹 Lists 📜

  • ✅ Ordered, ✅ Mutable, ✅ Allows Duplicates

  • 🔧 Modify using:

    append(), extend(), insert(), remove(), pop()

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

📌 Use when order matters and the data may change.

🧱 Tuples

  • ✅ Ordered, ❌ Immutable, ✅ Allows Duplicates

  • ⚡ Faster than lists, safe from accidental modification

coordinates = (10.0, 20.5)

📌 Use when data should not change (e.g., configuration, coordinates).

🔹 Sets 🔂

  • ❌ Unordered, ✅ Mutable, ❌ No Duplicates

  • ⚙️ Supports operations like union(), intersection(), difference()

unique_numbers = {1, 2, 3}

📌 Use for uniqueness, fast membership tests, and removing duplicates.

📚 Dictionaries 🔑

  • 🔑 Key-value pairs, ✅ Mutable, ✅ No duplicate keys

  • Fast lookup using keys

student = {"name": "Alice", "age": 21}

📌 Use when associating keys with values (like database records or API responses).

🔍 List vs Tuple vs Set – Quick Comparison

Feature

List

Tuple

Set

Dictionary

Syntax

[ ]

( )

{ }

{key: value}

Example

[1, 2, 3]

(1, 2, 3)

{1, 2, 3}

{"a": 1, "b": 2}

Ordered

✅ Yes

✅ Yes

❌ No*

✅ Yes**

Mutable

✅ Yes

❌ No

✅ Yes

✅ Yes

Allows duplicates

✅ Yes

✅ Yes

❌ No

Keys ❌, Values ✅

Indexing

✅ Yes

✅ Yes

❌ No

❌ By index

Key-Value pairs

❌ No

❌ No

❌ No

✅ Yes

Can be changed after creation

✅ Yes

❌ No

✅ Yes

✅ Yes

Use when

You need an ordered, changeable collection

You need an ordered, unchangeable collection

You need unique items

You need data in key-value form

✅ Tip:

  • Lists for general-purpose arrays and sequences.

  • Tuples when data must remain unchanged.

  • Sets when duplicates must be eliminated and membership tested quickly.

  • Dictionaries when data is associated with named identifiers.