Python Data Structures (Computer Science and Engineering Notes)

 

Python Data Structures

Data structures are fundamental to programming, providing ways to organize and manipulate data efficiently. Python offers a rich set of built-in data structures and also supports more advanced structures through libraries. These tools make Python versatile for everything from simple scripts to complex applications. GeeksForGeeks Real Python

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🌍 Built-in Data Structures

Lists

• Ordered, mutable collections.
• Can store heterogeneous data types.

fruits = ["apple", "banana", "cherry"]
fruits.append("orange")   # ["apple", "banana", "cherry", "orange"]

Tuples

• Ordered, immutable collections.
• Useful for fixed data sets.

coordinates = (10, 20)
print(coordinates[0])  # 10

Sets

• Unordered collections of unique elements.
• Efficient for membership tests.

unique_numbers = {1, 2, 3, 3}
print(unique_numbers)  # {1, 2, 3}

Dictionaries

• Key-value pairs, similar to hash maps.
• Fast lookups and updates.

student = {"name": "Alice", "age": 22}
student["grade"] = "A"

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🔄 Advanced Data Structures

Python’s collections module and other libraries extend functionality:

• OrderedDict: Maintains insertion order of keys.
• defaultdict: Provides default values for missing keys.
• ChainMap: Combines multiple dictionaries into one view.
• NamedTuple: Immutable, lightweight object-like tuples.
• Deque: Double-ended queue for fast appends/pops from both ends. Real Python

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✨ Strings as Data Structures

Strings in Python behave like immutable sequences of Unicode characters.

text = "Python"
print(text[0])   # P
print(text[::-1]) # nohtyP

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📊 Comparison Table

Data Structure	Ordered	Mutable	Unique Elements	Typical Use Case
List	Yes	Yes	No	General-purpose collection
Tuple	Yes	No	No	Fixed data sets
Set	No	Yes	Yes	Membership tests, deduplication
Dictionary	Keys unordered (pre-3.7), ordered (3.7+)	Yes	Keys unique	Fast lookups, mappings

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📖 Conclusion

Python’s data structures—lists, tuples, sets, and dictionaries—form the foundation of everyday programming. With advanced structures like OrderedDict, defaultdict, and deque, Python provides flexibility for specialized needs. Mastering these tools allows developers to write efficient, clean, and scalable code.