{"id":596,"date":"2020-10-17T05:02:15","date_gmt":"2020-10-17T05:02:15","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=596"},"modified":"2025-03-27T03:04:10","modified_gmt":"2025-03-27T03:04:10","slug":"python-set-union","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-basics\/python-set-union\/","title":{"rendered":"Python Set Union"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn how to union two or more sets by using the Python set union()<\/code> or set union operator (|).<\/p>\n\n\n\n

Introduction to the set union #<\/a><\/h2>\n\n\n\n

The union of two sets<\/a> returns a new set that contains distinct elements from both sets.<\/p>\n\n\n\n

Suppose that you have the following sets:<\/p>\n\n\n

s1 = {'Python'<\/span>, 'Java'<\/span>}\ns2 = {'C#'<\/span>, 'Java'<\/span>}<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
The union of the s1 and s2 sets returns the following set:<\/p>\n\n\n
{'Java'<\/span>,'Python'<\/span>, 'C#'<\/span>}<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
Typically, you use the Venn diagram to illustrate the union of two sets. For example:<\/p>\n\n\n\n
\"Python<\/figure>\n\n\n\n
Union sets using union() method #<\/a><\/h2>\n\n\n\n
In Python, to union two or more sets, you use the union()<\/code> method:<\/p>\n\n\n
new_set = set<\/span>.union(another_set, ...)<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
The following example shows how to union the s1<\/code> and s2<\/code> sets:<\/p>\n\n\n
s1 = {'Python'<\/span>, 'Java'<\/span>}\ns2 = {'C#'<\/span>, 'Java'<\/span>}\n\ns = s1.union(s2)\n\nprint<\/span>(s)<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
{'Python'<\/span>, 'Java'<\/span>, 'C#'<\/span>}<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
Union sets using the | operator #<\/a><\/h2>\n\n\n\n
Python provides you with the set union operator |<\/code> that allows you to union two sets:<\/p>\n\n\n
new_set = set1 | set2<\/code><\/span><\/pre>\n\n\n
The set union operator (|<\/code>) returns a new set that consists of distinct elements from both set1<\/code> and set2<\/code>.<\/p>\n\n\n\n
The following example shows how to use the union operator (|<\/code>) to union the s1<\/code> and s2<\/code> sets:<\/p>\n\n\n
s1 = {'Python'<\/span>, 'Java'<\/span>}\ns2 = {'C#'<\/span>, 'Java'<\/span>}\n\ns = s1 | s2\n\nprint<\/span>(s)<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
{'Java'<\/span>, 'C#'<\/span>, 'Python'<\/span>}<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
The union() method vs. set union operator #<\/a><\/h2>\n\n\n\n
The union()<\/code> method accepts one or more iterables<\/a>, converts the iterables to sets, and performs the union.<\/p>\n\n\n\n
The following example shows how to pass a list<\/a> to the union()<\/code> method:<\/p>\n\n\n
rates = {1<\/span>, 2<\/span>, 3<\/span>}\nranks = [2<\/span>, 3<\/span>, 4<\/span>]\n\nratings = rates.union(ranks)\n\nprint<\/span>(ratings)<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
{1, 2, 3, 4}<\/code><\/span><\/pre>\n\n\n
However, the union operator (|<\/code>) only allows sets, not iterables like the union()<\/code> method.<\/p>\n\n\n\n
The following example causes an error:<\/p>\n\n\n
rates = {1, 2, 3}\nranks = [2, 3, 4]\n\nratings = rates | ranks<\/code><\/span><\/pre>\n\n\n
Try it<\/a><\/p>\n\n\n\n
Error:<\/p>\n\n\n
TypeError<\/span>: unsupported operand type(s) for<\/span> |: 'set'<\/span> and 'list'<\/span><\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
In conclusion, the union()<\/code> method accepts the iterables while the union operator only allows sets.<\/p>\n\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n