Python中的 Union()函数

Python set Union()函数返回一个新集合，其中包含原始集合中的所有项目。

两个给定集合的并集是包含两个集合的所有元素的最小集合。两个给定集合 A 和 B 的并集是由 A 的所有元素和 B 的所有元素组成的集合，使得没有元素重复。

表示集合并集的符号是“U”

例子：

Input: Let set A = {2, 4, 5, 6} and set B = {4, 6, 7, 8}

Output: {2, 4, 5, 6, 7, 8} 

Explanation: Taking every element of both the sets A and B, without repeating any element, we get a new set = {2, 4, 5, 6, 7, 8}.This new set contains all the elements of set A and all the elements of set B with no repetition of elements and is named as union of set A and B.  

Python set Union() 语法：

set1.union(set2, set3, set4….) 

In parameters, any number of sets can be given

Python set Union() 返回值：

The union() function 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. 

Python set Union() 方法的示例：

示例 1：使用Python set Union() 方法

Python3

# Python3 program for union() function
 
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))

输出：

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

示例 2：使用 | 设置联合操作员

我们可以使用“|”运算符来查找集合的并集。

Python3

# Python3 program for union with | operator
 
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)

输出：

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