Union() function in Python

• Difficulty Level : Medium
• Last Updated : 09 Aug, 2022

Python set Union() Method returns a new set which contains all the items from the original set.

Union of two given sets is the set which contains all the elements of both the sets. The union of two given sets A and B is a set which consists of all the elements of A and all the elements of B such that no element is repeated.

The symbol for denoting union of sets is ‘U’

Python set Union() Method Syntax:

Syntax: set1.union(set2, set3, set4….)

Parameters: zero or more sets

Return: Returns a set, which has the union of all sets(set1, set2, set3…) with set1. It returns a copy of set1 only if no parameter is passed.

Python3

 `A ``=` `{``2``, ``4``, ``5``, ``6``}``B ``=` `{``4``, ``6``, ``7``, ``8``}` `print``(``"A U B:"``, A.union(B))`

Output:

`A U B: {2, 4, 5, 6, 7, 8}`

Python3

 `set1 ``=` `{``2``, ``4``, ``5``, ``6``}``set2 ``=` `{``4``, ``6``, ``7``, ``8``}``set3 ``=` `{``7``, ``8``, ``9``, ``10``}` `# union of two sets``print``(``"set1 U set2 : "``, set1.union(set2))` `# union of three sets``print``(``"set1 U set2 U set3 :"``, set1.union(set2, set3))`

Output:

```set1 U set2 :  {2, 4, 5, 6, 7, 8}
set1 U set2 U set3 : {2, 4, 5, 6, 7, 8, 9, 10}```

Example 2: Python Set Union Using the | Operator

We can use “|” operator to find the union of the sets.

Python3

 `set1 ``=` `{``2``, ``4``, ``5``, ``6``}``set2 ``=` `{``4``, ``6``, ``7``, ``8``}``set3 ``=` `{``7``, ``8``, ``9``, ``10``}` `# union of two sets``print``(``"set1 U set2 : "``, set1 | set2)` `# union of three sets``print``(``"set1 U set2 U set3 :"``, set1 |set2 | set3)`

Output:

```set1 U set2 :  {2, 4, 5, 6, 7, 8}
set1 U set2 U set3 : {2, 4, 5, 6, 7, 8, 9, 10}```

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