Python Set union() method

Python Set union() method

The set.union() method in Python returns a set that contains all items from the original set and all items from the specified sets.

Syntax

set.union(set1, set2...)

Parameter

set1- This parameter represents the first set to search for equal items

set2- This argument signifies the other set to search for equal items.

One can compare as many sets as needed, only need to separate the sets with a comma.  

Return

This method returns a new set with distinct elements from all the sets and writing the common elements between both the sets only once.

Example 1

# Python program explaining
# the set.union() method
# initializing the set1
set1 = {1,2,3,4,5,6}
# printing the actual set 1
print("Set 1:",set1)
# initializing the set2 
set2 = {2,7,8,6,5}
# printing the actual set 2
print("Set 2:",set2) 
# returns a new set with different items from all the sets and 
#writing the common elements between both the sets only once
Union= set1.union(set2)
print("A U B: ",Union) 

Output

Set 1: {1, 2, 3, 4, 5, 6}
Set 2: {8, 2, 5, 6, 7}
A U B:  {1, 2, 3, 4, 5, 6, 7, 8} 

Example 2

# Python program explaining
# the set.union() method
# initializing a list of fruits
A = {'apple', 'watermelon', 'mango','guava','orange','Lichi'} 
# initializing the summer fruits
B = {'Mushmelon', 'watermelon', 'mango','Blueberry'}
# initializing the specifically the winter fruits 
C= {'apple','guava','orange','Grapes'}
# will return the unique elements in both the sets
print('A U B =', A.union(B))
print('B U C =', B.union(C)) 
#passing two set parameters in the union method
# will return the unique items from all the sets
print('A U B U C =', A.union(B, C)) 
# passing only one argument
print('A.union() = ', A.union()) 

Output

A U B = {'mango', 'apple', 'watermelon', 'Mushmelon', 'orange', 'Lichi', 'guava', 'Blueberry'}
B U C = {'mango', 'Mushmelon', 'apple', 'orange', 'guava', 'Grapes', 'watermelon', 'Blueberry'}
A U B U C = {'mango', 'apple', 'Mushmelon', 'orange', 'Lichi', 'guava', 'Grapes', 'watermelon', 'Blueberry'} 
 A.union() =  {'mango', 'apple', 'watermelon', 'orange', 'Lichi', 'guava'} 

Example 3

# Python program explaining
# the set.union() method
A = {1,2,3,4,5,6}
B = {2,4,6,8 } 
print("Printing the union by two different method>>>")
# the operator '|' is used to get the union for two sets
print("By '|' operator\n A U B:", A | B)
# using the set.union() method 
print("Bu using the set.union() method\n A U B:",A.union(B)) 

Output

Printing the union by two different method>>>
By '|' operator
A U B: {1, 2, 3, 4, 5, 6, 8}
Bu using the set.union() method
A U B: {1, 2, 3, 4, 5, 6, 8}