Python Tutorials · Python Sets

Join Sets

Learn all about Join Sets in this comprehensive tutorial.

5 min read beginner

Loop Sets

Frozenset

•There are several ways to join two or more sets in Python.
•The union() method returns a new set with all items from both sets.
•All the joining methods and operators can be used to join multiple sets.
•The union() method allows you to join a set with other data types, like lists or tuples.
•The update() method inserts all items from one set into another.
•Keep ONLY the duplicates
•The difference() method will return a new set that will contain only the items from the first set that are not present in the other set.
•The symmetric_difference() method will keep only the elements that are NOT present in both sets.

Join Sets

There are several ways to join two or more sets in Python.

The union() and update() methods joins all items from both sets.

The intersection() method keeps ONLY the duplicates.

The difference() method keeps the items from the first set that are not in the other set(s).

The symmetric_difference() method keeps all items EXCEPT the duplicates.

Union

The union() method returns a new set with all items from both sets.

python

set1 = {"a", "b", "c"}set2 = {1, 2, 3}
  set3 = set1.union(set2)print(set3)

You can use the | operator instead of the union() method, and you will get the same result.

python

set1 = {"a", "b", "c"}set2 = {1, 2, 3}
  set3 = set1 | set2print(set3)

Join Multiple Sets

All the joining methods and operators can be used to join multiple sets.

When using a method, just add more sets in the parentheses, separated by commas:

python

set1 = {"a", "b", "c"}set2 = {1, 2, 3}set3 = {"Alice", "Elena"}set4 = {"apple", 
  "bananas", "cherry"}
  myset = set1.union(set2, set3, set4)print(myset)

When using the | operator, separate the sets with more | operators:

python

set1 = {"a", "b", "c"}set2 = {1, 2, 3}set3 = {"Alice", "Elena"}set4 = {"apple", 
  "bananas", "cherry"}
  myset = set1 | set2 | set3 |set4print(myset)

Join a Set and a Tuple

The union() method allows you to join a set with other data types, like lists or tuples.

The result will be a set.

python

val_1 = {"a", "b", "c"}val_2 = (1, 2, 3)
  z = val_1.union(val_2)print(z)

Note: Note: The | operator only allows you to join sets with sets, and not with other data types like you can with the union() method.

Update

The update() method inserts all items from one set into another.

The update() changes the original set, and does not return a new set.

python

set1 = {"a", "b" , "c"}set2 = {1, 2, 3}
  set1.update(set2)print(set1)

Note: Note: Both union() and update() will exclude any duplicate items.

Intersection

Keep ONLY the duplicates

The intersection() method will return a new set, that only contains the items that are present in both sets.

python

set1 = {"apple", "banana", "cherry"}set2 = {"google", "microsoft", "apple"}
  set3 = set1.intersection(set2)print(set3)

You can use the & operator instead of the intersection() method, and you will get the same result.

python

set1 = {"apple", "banana", "cherry"}set2 = {"google", "microsoft", "apple"}
  set3 = set1 
  & set2print(set3)

Note: Note: The & operator only allows you to join sets with sets, and not with other data types like you can with the intersection() method.

The intersection_update() method will also keep ONLY the duplicates, but it will change the original set instead of returning a new set.

python

set1 = {"apple", "banana", "cherry"}set2 = {"google", "microsoft", "apple"}
set1.intersection_update(set2)print(set1)

The values True and 1 are considered the same value. The same goes for False and 0.

python

set1 = {"apple", 1,  "banana", 0, "cherry"}
  set2 = {False, "google", 
  1, "apple", 2, True}
set3 = set1.intersection(set2)print(set3)

Difference

The difference() method will return a new set that will contain only the items from the first set that are not present in the other set.

python

set1 = {"apple", "banana", "cherry"}set2 = {"google", "microsoft", "apple"}
set3 = set1.difference(set2)print(set3)

You can use the - operator instead of the difference() method, and you will get the same result.

python

set1 = {"apple", "banana", "cherry"}set2 = {"google", "microsoft", "apple"}
  set3 = set1 - set2print(set3)

Note: Note: The - operator only allows you to join sets with sets, and not with other data types like you can with the difference() method.

The difference_update() method will keep the items from the first set that are not in the other set, but it will change the original set instead of returning a new set.

python

set1 = {"apple", "banana", "cherry"}set2 = {"google", "microsoft", "apple"}
set1.difference_update(set2)print(set1)

Symmetric Differences

The symmetric_difference() method will keep only the elements that are NOT present in both sets.

python

set1 = {"apple", "banana", "cherry"}set2 = {"google", "microsoft", "apple"}
set3 = set1.symmetric_difference(set2)print(set3)

You can use the ^ operator instead of the symmetric_difference() method, and you will get the same result.

python

set1 = {"apple", "banana", "cherry"}set2 = {"google", "microsoft", "apple"}
  set3 = set1 ^ set2print(set3)

Note: Note: The ^ operator only allows you to join sets with sets, and not with other data types like you can with the symmetric_difference() method.

The symmetric_difference_update() method will also keep all but the duplicates, but it will change the original set instead of returning a new set.

python

set1 = {"apple", "banana", "cherry"}set2 = {"google", "microsoft", "apple"}
set1.symmetric_difference_update(set2)print(set1)

Module quiz

2 questions

Which of the following is true about Join Sets?

It is strictly typedIt is evaluated at runtimeIt requires explicit memory managementIt is deprecated

What is the most common pitfall when working with Join Sets?

SyntaxErrorIndentationErrorNameErrorTypeError

Answer all questions to submit.

Loop Sets

Frozenset

Join Sets

AI Summary

Join Sets

Union

Join Multiple Sets

Join a Set and a Tuple

Update

Intersection

Difference

Symmetric Differences

Module quiz