Python Sets(advanced)
Table of Contents
Description
A set is an unordered collection of unique items. Beyond basics, advanced set concepts include:
Set operations: union, intersection, difference, symmetric difference
Set comprehension
Frozen sets
Subset/superset checks
Removing duplicates from iterables
Performance use-cases (e.g., fast membership testing)
Prerequisites
- Basic understanding of:
What sets are
Iterable data types (lists, tuples)
Boolean logic and operations
Examples
Here's a simple program in Python:
✅ Set Operations
a = {1, 2, 3, 4}
b = {3, 4, 5, 6}
# Union (combine all unique elements)
print(a | b) # {1, 2, 3, 4, 5, 6}
# Intersection (common elements)
print(a & b) # {3, 4}
# Difference (elements in a not in b)
print(a - b) # {1, 2}
# Symmetric Difference (elements in a or b, but not both)
print(a ^ b) # {1, 2, 5, 6}
✅ Set Comprehension
# Create a set of squares from 0 to 4
squares = {x ** 2 for x in range(5)}
print(squares) # {0, 1, 4, 9, 16}
✅ Removing Duplicates from a List
nums = [1, 2, 2, 3, 4, 4, 5]
# Convert to set to remove duplicates
unique = list(set(nums))
print(unique) # [1, 2, 3, 4, 5]
✅ Frozen Sets
# Immutable version of set
frozen = frozenset([1, 2, 3])
# frozen.add(4) # ❌ Error: 'frozenset' object has no attribute 'add'
print(frozen) # frozenset({1, 2, 3})
✅ Subset and Superset Checks
a = {1, 2}
b = {1, 2, 3}
print(a.issubset(b)) # True
print(b.issuperset(a)) # True
✅ Disjoint Sets
# True if sets have no common elements
print({1, 2}.isdisjoint({3, 4})) # True
print({1, 2}.isdisjoint({2, 3})) # False
Real-World Applications
Fast duplicate removal in large datasets
Keyword filtering in NLP tasks
Unique identifiers (like tags, IDs)
Mathematical set operations in simulations
Permissions and roles management in applications
Where topic Can Be Applied
Data preprocessing in machine learning
Search optimization (e.g., auto-suggestions)
Web scraping: Keep track of already visited URLs
Graph theory: Set operations for neighbors and paths
Access control: Set-based role checking
Resources
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Interview Questions
What makes sets faster than lists for membership testing?
How does set() remove duplicates from a list?
Explain difference between |, &, -, and ^ in sets.
What is a frozenset and when would you use it?
How do sets handle duplicates internally?
What’s the difference between issubset() and issuperset()?