Returns a set with items from all the specified sets
Usage
The union()
method returns a new set containing all items from all the specified sets, with no duplicates.
You can specify as many sets as you want, just separate each set with a comma.
If you want to modify the original set instead of returning a new one, use update() method.
Syntax
set.union(set1,set2…)
Parameter | Condition | Description |
set1, set2… | Optional | A comma-separated list of one or more sets to merge with. |
Basic Example
# Perform union of two sets
A = {'red', 'green', 'blue'}
B = {'yellow', 'red', 'orange'}
print(A.union(B))
# Prints {'blue', 'green', 'yellow', 'orange', 'red'}

Equivalent Operator |
Set union can be performed with the |
operator as well.
A = {'red', 'green', 'blue'}
B = {'yellow', 'red', 'orange'}
# by method
print(A.union(B))
# Prints {'blue', 'green', 'yellow', 'orange', 'red'}
# by operator
print(A | B)
# Prints {'blue', 'green', 'yellow', 'orange', 'red'}
Union of Multiple Sets
Multiple sets can be specified with either the operator or the method.
A = {'red', 'green', 'blue'}
B = {'yellow', 'orange', 'red'}
C = {'blue', 'red', 'black'}
# by method
print(A.union(B,C))
# Prints {'blue', 'green', 'yellow', 'orange', 'black', 'red'}
# by operator
print(A | B | C)
# Prints {'blue', 'green', 'yellow', 'orange', 'black', 'red'}