# set() and frozenset() functions generate mutable and immutable sets, respectively. : Set « Collections « Python Tutorial

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 Python Tutorial » Collections » Set
9.3.18.set() and frozenset() functions generate mutable and immutable sets, respectively.
 ```print set() print set([]) print set(()) print set('BC') print frozenset(['foo', 'bar']) f = open('numbers', 'w') for i in range(5):     f.write('%d\n' % i)      f.close() f = open('numbers', 'r') print set(f) f.close()```
 9.3.Set 9.3.1. Set operations 9.3.2. How to Create and Assign Set Types 9.3.3. How to Access Values in Sets 9.3.4. How to Update Sets 9.3.5. Membership (in, not in) 9.3.6. Set Equality/Inequality 9.3.7. Subset Of/Superset Of 9.3.8. Union ( | ) 9.3.9. Intersection ( & ) 9.3.10. Difference/Relative Complement ( - ) 9.3.11. Symmetric Difference ( ^ ) 9.3.12. Mixed Set Type Operations 9.3.13. (Union) Update ( | = ) 9.3.14. Retention/Intersection Update ( &= ) 9.3.15. Difference Update ( - = ) 9.3.16. Symmetric Difference Update ( ^ = ) 9.3.17. len() returns the number of elements 9.3.18. set() and frozenset() functions generate mutable and immutable sets, respectively.