Python集合

1集合是一个无序的，不重复的数据组合，它的主要作用如下(set和dict类似，也是一组key的集合，但不存储value。由于key不能重复，所以，在set中，没有重复的key):

　　去重，把一个列表变成集合，就自动去重了

　　关系测试，测试两组数据之前的交集、差集、并集等关系

2（去重）

# -*- coding:utf-8 -*-
s={1,2,3,4,5,1,2,12,"tin",("tj",120),"tin",("tj",120)}
print(type(s))
print(s)

输出结果：

<class 'set'>
{1, 2, 3, 4, 5, 'tin', 12, ('tj', 120)}

（关系测试）

交集:

# -*- coding:utf-8 -*-
s={1,2,3,4,5,1,2,12,"tin",("tj",120),"tin",("tj",120)}
s2={123,23,4,5,6,7,8,}
#交集，把相同的元素取出来
print(s2.intersecti(s))     #或 print(s2 & s)

输出结果：

{4, 5}

并集

s={1,2,3,4,5,1,2,12,"tin",("tj",120),"tin",("tj",120)}
s2={123,23,4,5,6,7,8,}  #并集
print(s2.union(s))     #或  print(s2 | s)

输出结果：

{1, 2, 3, 4, 5, 6, 7, 8, ('tj', 120), 12, 'tin', 23, 123}

差集

s={1,2,3,4,5,1,2,12,"tin",("tj",120),"tin",("tj",120)}
s2={123,23,4,5,6,7,8,}   #差集
print(s2.difference(s))  # 或 print(s2-s)

输出结果：

 {6, 7, 8, 23, 123} 

对称差集

s={1,2,3,4,5,1,2,12,"tin",("tj",120),"tin",("tj",120)}
s2={123,23,4,5,6,7,8,}    
print(s2.symmetric_difference(s))   #或 print(s2 ^ s)

输入结果：

 {1, 2, 3, 6, 7, 8, 12, 'tin', 23, ('tj', 120), 123} 

随机删除元素：

s={1,2,3,4,5,1,2,12,"tin",("tj",120),"tin",("tj",120)}
s2={123,23,4,5,6,7,8,}
print(s2.pop())   #pop 随机删除元素

输出结果：4

删除元素（可以任意删除一项）：

s2={123,23,4,5,6,7,8,}
s.remove(2)
print(s)

输出结果：

{1, 3, 4, 5, 'tin', 12, ('tj', 120)}

父集：

s={1,2,3,4,5,1,2,12,"tin",("tj",120),"tin",("tj",120)}
s2={123,23,4,5,6,7,8,}
s.remove(2)
print(s)
print(s2.issuperset(s))

输出结果：

{1, 3, 4, 5, 12, ('tj', 120), 'tin'}
False

子集：

s={1,2,3,4,5,1,2,12,"tin",("tj",120),"tin",("tj",120)}
s2={123,23,4,5,6,7,8,}
s.remove(2)
print(s)
print(s2.issubset(s))

输出结果：

{1, 3, 4, 5, 'tin', 12, ('tj', 120)}
False

对称并集：

s={1,2,3,4,5,1,2,12,"tin",("tj",120),"tin",("tj",120)}
s2={123,23,4,5,6,7,8,}
s.remove(2)
print(s)
s2.difference_update(s)
print(s2)

输出结果：

{'tin', 1, 3, 4, 5, ('tj', 120), 12}
{6, 7, 8, 23, 123}

添加元素：

s={1,2,3,4,5,1,2,12,"tin",("tj",120),"tin",("tj",120)}
s2={123,23,4,5,6,7,8,}
s2.add(18)
print(s2)
s.add(21)
print(s)

输出结果：

{4, 5, 6, 7, 8, 18, 23, 123}
{('tj', 120), 1, 2, 3, 4, 5, 12, 'tin', 21}

合并多项元素：

s={1,2,3,4,5,1,2,12,"tin",("tj",120),"tin",("tj",120)}
s2={123,23,4,5,6,7,8,}
s.update(s2)
print(s)

输出结果：

{1, 2, 3, 4, 5, 6, 7, 8, 12, 23, 'tin', 123, ('tj', 120)}