Python：集合

>>> s  = set(‘python‘)   
>>> s
{‘p‘, ‘t‘, ‘y‘, ‘h‘, ‘o‘, ‘n‘}

>>> l1 = [‘python‘,‘pingy‘]
>>> s = set(l1)
>>> s
{‘pingy‘, ‘python‘}

>>> s = set(‘hello‘)
>>> s    
{‘h‘, ‘e‘, ‘l‘, ‘o‘}     #‘hello‘中有两个‘l‘，集合会去掉重复的元素。

>>> s = set(‘python‘)
>>> s
{‘p‘, ‘t‘, ‘y‘, ‘h‘, ‘o‘, ‘n‘}
>>> s.add(‘abc‘)     #增加元素
>>> s
{‘p‘, ‘t‘, ‘y‘, ‘abc‘, ‘h‘, ‘o‘, ‘n‘}

>>> s.update(‘bcd‘)  
>>> s
{‘p‘, ‘t‘, ‘y‘, ‘abc‘, ‘c‘, ‘b‘, ‘d‘, ‘h‘, ‘o‘, ‘n‘}

>>> se = set(‘linux‘)
>>> se
{‘i‘, ‘x‘, ‘u‘, ‘l‘, ‘n‘}
>>> s.update(se)   #把se集合更新到s集合中
>>> s
{‘p‘, ‘u‘, ‘t‘, ‘y‘, ‘x‘, ‘abc‘, ‘c‘, ‘b‘, ‘d‘, ‘i‘, ‘h‘, ‘l‘, ‘o‘, ‘n‘}

>>> s
{‘p‘, ‘u‘, ‘t‘, ‘y‘, ‘x‘, ‘abc‘, ‘c‘, ‘b‘, ‘d‘, ‘i‘, ‘h‘, ‘l‘, ‘o‘, ‘n‘}
>>> s.remove(‘abc‘)    #删除指定元素
>>> s
{‘p‘, ‘u‘, ‘t‘, ‘y‘, ‘x‘, ‘c‘, ‘b‘, ‘d‘, ‘i‘, ‘h‘, ‘l‘, ‘o‘, ‘n‘}

>>> se
{‘i‘, ‘x‘, ‘u‘, ‘l‘, ‘n‘}
>>> del se      #删除集合
>>> s1
{‘a‘, ‘m‘, ‘n‘}
>>> s1.clear()   #清空集合
>>> s1
set()

>>> s1
{‘a‘, ‘m‘, ‘n‘}
>>> s2
{‘a‘, ‘m‘, ‘o‘, ‘w‘, ‘n‘}
>>> s1<s2
True

>>> s1
{‘a‘, ‘m‘, ‘n‘}
>>> s2
{‘a‘, ‘m‘, ‘o‘, ‘w‘, ‘n‘}
>>> s1<s2
True
>>> s1 & s2   #交集
{‘a‘, ‘m‘, ‘n‘}
>>> s1 | s2    #并集
{‘w‘, ‘a‘, ‘m‘, ‘o‘, ‘n‘}
>>> s2 -s1   #差集
{‘w‘, ‘o‘}

>>> l = [1,2,3,4,5,6,4,3,6,7,9,12,2]
>>> l
[1, 2, 3, 4, 5, 6, 4, 3, 6, 7, 9, 12, 2]

>>> list(set(l))
[1, 2, 3, 4, 5, 6, 7, 9, 12]