Documentation Index Fetch the complete documentation index at: https://python.datalumina.com/llms.txt
Use this file to discover all available pages before exploring further.
What are sets? Sets are collections that only store unique values. They automatically remove duplicates.
Think of sets like:
A bag of unique marbles
Guest list (each person once)
Unique tags or categories
Creating sets You can create sets two ways: with set() or with curly braces {} (but only when it has values).
# Empty set (careful!) empty_set = set () # NOT {} - that's a dict! # Set with values - both ways work numbers = { 1 , 2 , 3 , 4 , 5 } fruits = set ([ "apple" , "banana" , "orange" ]) # From a list (removes duplicates) scores = [ 85 , 90 , 85 , 92 , 90 ] unique_scores = set (scores) # {85, 90, 92}
Use set() for empty sets, not {}. Empty curly braces create a dictionary!
Basic operations colors = { "red" , "blue" } # Add items colors.add( "green" ) print (colors) # {'red', 'blue', 'green'} # Remove items colors.remove( "blue" ) # Error if not found colors.discard( "yellow" ) # No error if not found # Check membership if "red" in colors: print ( "Red is available" )
Common uses Remove duplicates names = [ "Alice" , "Bob" , "Alice" , "Charlie" , "Bob" ] unique_names = list ( set (names)) print (unique_names) # ['Alice', 'Bob', 'Charlie']
Fast membership testing allowed_users = { "alice" , "bob" , "charlie" } if "alice" in allowed_users: # Very fast! print ( "Access granted" )
Common mistakes
# Wrong - creates empty dict empty = {} # Right - use set() empty = set ()
# Order is not guaranteed! numbers = { 3 , 1 , 4 , 1 , 5 } print (numbers) # Could be any order # Use list if order matters ordered = [ 3 , 1 , 4 , 1 , 5 ]
What’s next? Congratulations! You’ve completed Python Basics. Ready to start building programs?
Building Programs Learn about functions
