2 -10 集合set

iphone7 = [‘alex‘,‘rain‘,‘jack‘,‘tom‘]
iphone8 = [‘alex‘,‘shanshan‘,‘jack‘,‘tom‘]
both_list = []
for name in iphone7:
    if name in iphone8:
        both_list.append(name)
print(both_list)
#运行结果
[‘alex‘, ‘jack‘, ‘tom‘]

集合中的元素有三个特征：

1.确定性（元素必须可hash）
2.互异性（去重）
3.无序性（集合中的元素没有先后之分），如集合{3,4,5}和{3,5,4}算作同一个集合。

# 查看所有方法
>>> dir(s)
[‘__and__‘, ‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__dir__‘, ‘__doc__‘, ‘__eq__‘, ‘__format__‘, ‘__ge__‘, ‘__getatt
ribute__‘, ‘__gt__‘, ‘__hash__‘, ‘__iand__‘, ‘__init__‘, ‘__ior__‘, ‘__isub__‘, ‘__iter__‘, ‘__ixor__‘, ‘__le__‘, ‘__len_
_‘, ‘__lt__‘, ‘__ne__‘, ‘__new__‘, ‘__or__‘, ‘__rand__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__ror__‘, ‘__rsub__‘
, ‘__rxor__‘, ‘__setattr__‘, ‘__sizeof__‘, ‘__str__‘, ‘__sub__‘, ‘__subclasshook__‘, ‘__xor__‘, ‘add‘, ‘clear‘, ‘copy‘, ‘
difference‘, ‘difference_update‘, ‘discard‘, ‘intersection‘, ‘intersection_update‘, ‘isdisjoint‘, ‘issubset‘, ‘issuperset
‘, ‘pop‘, ‘remove‘, ‘symmetric_difference‘, ‘symmetric_difference_update‘, ‘union‘, ‘update‘]
>>>

# 方法的帮助
>>> help(s.clear)

Help on built-in function clear:

clear(...) method of builtins.set instance
    Remove all elements from this set.

>>> iphone7
{‘rain‘, ‘jack‘, ‘alex‘, ‘tom‘}
>>> iphone8
{‘shanshan‘, ‘jack‘, ‘alex‘, ‘tom‘}

# 交集
>>> iphone7.intersection(iphone8)
{‘jack‘, ‘alex‘, ‘tom‘}
>>> iphone7 & iphone8
{‘jack‘, ‘alex‘, ‘tom‘}
>>>

#差集
>>> iphone7.difference(iphone8)
{‘rain‘}
>>> iphone7 - iphone8
{‘rain‘}
>>>
>>> iphone8.difference(iphone7)
{‘shanshan‘}
>>> iphone8 - iphone7
{‘shanshan‘}

#并集
>>> iphone7.union(iphone8)
{‘rain‘, ‘tom‘, ‘shanshan‘, ‘jack‘, ‘alex‘}
>>> iphone7 | iphone8
{‘rain‘, ‘tom‘, ‘shanshan‘, ‘jack‘, ‘alex‘}
>>>

# 对称差集
# 只买了iphone7 或者iphone8 的人
>>> iphone7.symmetric_difference(iphone8)
{‘shanshan‘, ‘rain‘}
>>> iphone7 ^ iphone8
{‘shanshan‘, ‘rain‘}

def difference_update(self, *args, **kwargs): # real signature unknown
        """ Remove all elements of another set from this set. """
        pass   

def intersection_update(self, *args, **kwargs): # real signature unknown
        """ Update a set with the intersection of itself and another. """
        pass