Sets in Python

In this tutorial, you will learn about the set data structure in python. How to create a set, how to add more data in a set, how to remove data in a set and more set operations.

Set is one of the four built-in data types such as list, tuple, set, dictionary. A set is a data structure used to store unique elements in an unordered fashion. Sets are used to store multiple items in a single variable. Set items are unordered, mutable and has no duplicate elements.

• Sets are defined by using the curly braces {} or the set() function.

Creating sets:

1. Using Curly braces:-

   my_set = {1,2,3,4,5}

2. Using set() function:-

   my_set = set([1,2,3,4,5])

3. An empty set must be created by using the set() function, as curly braces {} creates an empty dictionary.

   empty_set = set()

Basic Set operations:-

• Add
• Remove
• Discard
• Clear

In the below example set operations are included: Adding the element and Removing the element.

my_set = {1,2,3,4,5}
my_set.add(6)
my_set.remove(5)
print(my_set)

Output:

{1, 2, 3, 4, 6}

discard():
Discard() method will removes the element if it is found, does nothing if not found(it will not return any error).

clear():
It will empties the set.

Set Operations:

1. Union:
   Union operator is used to combine the different sets using  “|” operator or union() method and it will also remove duplicate values.
   Using | operator:

   set1 = {1, 2, 3}
   set2 = {one, two, three}
   union_set = set1 | set2
   print(union_set)

   Output:
   {1, 2, 3, one, two, three}

   Using union() method:

   set1 = {1, 2, 3}
   set2 = {2, 4, 5}
   union_set = set1.union(set2)

   Output:
   {1, 2, 3, 4, 5}

2. Intersection:
   Intersection operator is used to find the common values between two sets and return those values in a set using the intersection() method or the “&” operator. In this example I have included both the methods.

   set1 = {1, 2, 3, 4, 5}
   set2 = {2, 4, 6, 8}
   intersection_set = set1&set2
   intersection_Set = set1.intersection(set2)
   print(intersection_set)
   print(intersection_Set)

   Output:
   {2, 4}
   {2, 4}

3. Difference:
   Difference method will display the elements in first set but not in the second set using the “-” operator or difference() method.

   set1 = {1, 2, 3}
   set2 = {3, 4, 5}
   difference_set = set1 - set2 
   difference_Set = set1.difference(set2)
   print(difference_set)
   print(difference_Set)

   Output:
   {1, 2}
   {1, 2}

4. Symmetric Difference:
   It will returns elements in either set but not in both sets using “^” operator and symmetric_difference() method.

   set1 = {1, 2, 3}
   set2 = {3, 4, 5}
   symmetric_difference_set = set1 ^ set2
   symmetric_difference_Set = set1.symmetric_difference(set2)
   print(symmetric_difference_set)
   print(symmetric_difference_Set)

   Output:
   {1, 2, 4, 5}
   {1, 2, 4, 5}