Unlock the Power of Sets in Python
What is a Set?
A set is a collection of unique data, ensuring that elements within it cannot be duplicated. This makes sets ideal for storing information like student IDs, where duplicates are not allowed.
Creating a Set in Python
In Python, you can create a set by placing all the elements inside curly braces {}, separated by commas. A set can have any number of items, and they can be of different types, such as integers, floats, tuples, strings, and more. However, a set cannot have mutable elements like lists, sets, or dictionaries as its elements.
Example:
numbers = {1, 2, 3, 4, 5}
strings = {'apple', 'banana', 'cherry'}
mixed_types = {1, 'a', 2.5, ('x', 'y')}
Creating an Empty Set
Creating an empty set can be a bit tricky. Empty curly braces {} will create an empty dictionary in Python. To create a set without any elements, you can use the set() function without any arguments.
Example:
empty_set = set()
empty_dictionary = {}
print(type(empty_set)) # <class 'et'>
print(type(empty_dictionary)) # <class 'dict'>
Handling Duplicate Items
Sets automatically eliminate duplicate items. If you try to include duplicate items in a set, they will be ignored.
Example:
numbers = {1, 2, 2, 3, 4, 4, 5}
print(numbers) # {1, 2, 3, 4, 5}
Adding and Updating Set Items
Sets are mutable, but they are unordered, so indexing has no meaning. You can use the add() method to add an item to a set and the update() method to update the set with items from other collection types.
Example:
“`
numbers = {1, 2, 3}
numbers.add(4)
print(numbers) # {1, 2, 3, 4}
techcompanies = {‘Google’, ‘Microsoft’, ‘Apple’}
companies = {‘Facebook’, ‘Amazon’}
companies.update(techcompanies)
print(companies) # {‘Facebook’, ‘Amazon’, ‘Google’, ‘Microsoft’, ‘Apple’}
“`
Removing an Element from a Set
You can use the discard() method to remove the specified element from a set.
Example:
languages = {'Java', 'Python', 'C++'}
languages.discard('Java')
print(languages) # {'Python', 'C++'}
Built-in Functions with Set
Python provides several built-in functions to perform different operations on a set, such as iterating over a set, finding the number of elements, and performing mathematical set operations.
Example:
“`
numbers = {1, 2, 3, 4, 5}
for num in numbers:
print(num)
print(len(numbers)) # 5
“`
Python Set Operations
Sets provide different built-in methods to perform mathematical set operations like union, intersection, subtraction, and symmetric difference.
Union of Two Sets
A = {1, 2, 3}
B = {3, 4, 5}
print(A | B) # {1, 2, 3, 4, 5}
Set Intersection
A = {1, 2, 3}
B = {2, 3, 4}
print(A & B) # {2, 3}
Difference between Two Sets
A = {1, 2, 3}
B = {2, 3, 4}
print(A - B) # {1}
Set Symmetric Difference
A = {1, 2, 3}
B = {2, 3, 4}
print(A ^ B) # {1, 4}
Checking if Two Sets are Equal
You can use the == operator to check whether two sets are equal or not.
Example:
A = {1, 2, 3}
B = {1, 2, 3}
if A == B:
print('Set A and Set B are equal')
Other Python Set Methods
There are many set methods available, including isdisjoint(), issubset(), issuperset(), and more.