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Beginner 18 min readModule: Module 4: Collections: Lists, Tuples, Dicts & Sets

Python Collections (Lists, Tuples, Dicts, Sets)

Master Python's built-in collection types, dictionary lookups, and set operations (union, intersection).

What You Will Learn in This Lesson

  • Lists (mutable ordered) vs Tuples (immutable ordered)
  • Dictionaries (key-value hash maps) with dict.get(key, default)
  • Sets for mathematical set operations (union |, intersection &)

Introduction & Core Concept

Python's built-in collection types are highly optimized C implementations designed for speed and flexibility.
WHY DOES THIS MATTER IN THE REAL WORLD?

Dictionary key lookups in Python operate in O(1) average time, making them ideal for high-speed indexing.

Dictionary & Set Operations

python
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student = {"id": "S101", "name": "Alex Dev", "gpa": 3.9}
 
# Safe dictionary lookup with default
major = student.get("major", "Undeclared")
print(f"Student: {student['name']} | Major: {major}")
 
skills_a = {"Python", "SQL", "Docker"}
skills_b = {"Docker", "Kubernetes", "AWS"}
common = skills_a & skills_b # Set intersection
print("Common Skills:", common)

Line-by-Line Technical Breakdown

1Tuples are hashable and can be used as dictionary keys, whereas lists cannot.

Try It Yourself (Interactive Editor)

Modify the code in real-time and click Run to test live browser output and console logs.

Intelligent Code Runner & Live Sandbox[PYTHON]
PYTHON SOURCE EDITOR
Interactive Live Code

Industry Best Practices & Professional Standards

  • Use set for fast O(1) membership testing (if item in my_set).

Lesson Summary & Core Takeaways

  • Collections form the backbone of Python data manipulation.