Python Union()用法及代码示例

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的并集是一个由A的所有元素和B的所有元素组成的集合，这样就不会重复任何元素。

表示集合并集的符号是“ U”。示例：

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.  

用法:

set1.union(set2, set3, set4….)
In parameters, any number of sets can be given

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.

以下是上述方法的Python3实现：

# 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}

实际应用：

在大多数概率问题中，需要集合并集的概念。