Python基础（四）-集合
数据类型总结：
1、按照数据可变不可变：
可变：列表、字典
不可变：数字、字符串、元组
x={'1':1}
print(id(x))
x.update({'2':2})
print(x)
print(id(x))
#执行结果
5584648
{'2': 2, '1': 1}
5584648
#列表亦同理 def a(x=[]): x.append(1) print(id(x)) return x print(a()) print(a()) #执行结果 14045576 [1] 14045576 [1, 1]
2、按照访问方式：
直接访问：数字
顺序访问：列表、元组、字符串
映射：字典
3、按照存放元素个数：
容器类型：列表、元组、字典
原子：数字、字符串
bytes类型
定义：存8bit整数，数据基于网络传输或内存变量存储到硬盘时需要转成bytes类型,字符串前置b代表为bytes类型
集合：
特点：无序；元素必须是不可变类型数据；不同元素（无重复元素）
属于可变类
集合创建：
#创建可变集合 a = set() b=set('hello') print(b) # {'o', 'e', 'l', 'h'} #创建不可变集合 nb = frozenset(b) print(nb) frozenset({'l', 'e', 'h', 'o'})
常用方法：
##增
1、add #一次只能添加一个集合元素
2、update #增加可迭代数据，把每个元素迭代更新到集合，可以更新多个数据
##删
1、remove() #删除的元素必须是集合中的元素，否则会报错
2、discard() #删除的元素可以不是集合中的元素
3、pop() #随机删除一个元素
4、clear() #清空
##判断
1、isdisjoint()
判断两个集合是否有交集，没有则返回 True
2、issubset()
a.issubset(b) 判断a 是否是b的子集，是则返回 True
3、issuperset()
a.issuperset() 判断a是否是b的父集合，是则返回 True
##浅复制
1、copy()
##运算
1、交集 & intersection
a.intersection(b) #a和b相同元素
2、并集 ^ union
a.union(b) #a和b组成新的集合
3、差集 - difference
a.difference(b) #存在a中，但不存在b中
4、symmetric_difference #对称差
a.symmetric_difference(b)== (a-b)^(b-a)
集合工厂函数：
class set(object): """ set() -> new empty set object set(iterable) -> new set object Build an unordered collection of unique elements. """ def add(self, *args, **kwargs): # real signature unknown """ Add an element to a set. This has no effect if the element is already present. """ pass def clear(self, *args, **kwargs): # real signature unknown """ Remove all elements from this set. """ pass def copy(self, *args, **kwargs): # real signature unknown """ Return a shallow copy of a set. """ pass def difference(self, *args, **kwargs): # real signature unknown """ 相当于s1-s2 Return the difference of two or more sets as a new set. (i.e. all elements that are in this set but not the others.) """ pass def difference_update(self, *args, **kwargs): # real signature unknown """ Remove all elements of another set from this set. """ pass def discard(self, *args, **kwargs): # real signature unknown """ 与remove功能相同，删除元素不存在时不会抛出异常 Remove an element from a set if it is a member. If the element is not a member, do nothing. """ pass def intersection(self, *args, **kwargs): # real signature unknown """ 相当于s1&s2 Return the intersection of two sets as a new set. (i.e. all elements that are in both sets.) """ pass def intersection_update(self, *args, **kwargs): # real signature unknown """ Update a set with the intersection of itself and another. """ pass def isdisjoint(self, *args, **kwargs): # real signature unknown """ Return True if two sets have a null intersection. """ pass def issubset(self, *args, **kwargs): # real signature unknown """ 相当于s1<=s2 Report whether another set contains this set. """ pass def issuperset(self, *args, **kwargs): # real signature unknown """ 相当于s1>=s2 Report whether this set contains another set. """ pass def pop(self, *args, **kwargs): # real signature unknown """ Remove and return an arbitrary set element. Raises KeyError if the set is empty. """ pass def remove(self, *args, **kwargs): # real signature unknown """ Remove an element from a set; it must be a member. If the element is not a member, raise a KeyError. """ pass def symmetric_difference(self, *args, **kwargs): # real signature unknown """ 相当于s1^s2 Return the symmetric difference of two sets as a new set. (i.e. all elements that are in exactly one of the sets.) """ pass def symmetric_difference_update(self, *args, **kwargs): # real signature unknown """ Update a set with the symmetric difference of itself and another. """ pass def union(self, *args, **kwargs): # real signature unknown """ 相当于s1|s2 Return the union of sets as a new set. (i.e. all elements that are in either set.) """ pass def update(self, *args, **kwargs): # real signature unknown """ Update a set with the union of itself and others. """ pass def __and__(self, *args, **kwargs): # real signature unknown """ Return self&value. """ pass def __contains__(self, y): # real signature unknown; restored from __doc__ """ x.__contains__(y) <==> y in x. """ pass def __eq__(self, *args, **kwargs): # real signature unknown """ Return self==value. """ pass def __getattribute__(self, *args, **kwargs): # real signature unknown """ Return getattr(self, name). """ pass def __ge__(self, *args, **kwargs): # real signature unknown """ Return self>=value. """ pass def __gt__(self, *args, **kwargs): # real signature unknown """ Return self>value. """ pass def __iand__(self, *args, **kwargs): # real signature unknown """ Return self&=value. """ pass def __init__(self, seq=()): # known special case of set.__init__ """ set() -> new empty set object set(iterable) -> new set object Build an unordered collection of unique elements. # (copied from class doc) """ pass def __ior__(self, *args, **kwargs): # real signature unknown """ Return self|=value. """ pass def __isub__(self, *args, **kwargs): # real signature unknown """ Return self-=value. """ pass def __iter__(self, *args, **kwargs): # real signature unknown """ Implement iter(self). """ pass def __ixor__(self, *args, **kwargs): # real signature unknown """ Return self^=value. """ pass def __len__(self, *args, **kwargs): # real signature unknown """ Return len(self). """ pass def __le__(self, *args, **kwargs): # real signature unknown """ Return self<=value. """ pass def __lt__(self, *args, **kwargs): # real signature unknown """ Return self<value. """ pass @staticmethod # known case of __new__ def __new__(*args, **kwargs): # real signature unknown """ Create and return a new object. See help(type) for accurate signature. """ pass def __ne__(self, *args, **kwargs): # real signature unknown """ Return self!=value. """ pass def __or__(self, *args, **kwargs): # real signature unknown """ Return self|value. """ pass def __rand__(self, *args, **kwargs): # real signature unknown """ Return value&self. """ pass def __reduce__(self, *args, **kwargs): # real signature unknown """ Return state information for pickling. """ pass def __repr__(self, *args, **kwargs): # real signature unknown """ Return repr(self). """ pass def __ror__(self, *args, **kwargs): # real signature unknown """ Return value|self. """ pass def __rsub__(self, *args, **kwargs): # real signature unknown """ Return value-self. """ pass def __rxor__(self, *args, **kwargs): # real signature unknown """ Return value^self. """ pass def __sizeof__(self): # real signature unknown; restored from __doc__ """ S.__sizeof__() -> size of S in memory, in bytes """ pass def __sub__(self, *args, **kwargs): # real signature unknown """ Return self-value. """ pass def __xor__(self, *args, **kwargs): # real signature unknown """ Return self^value. """ pass __hash__ = None 查看 查看
练习：
1 # 数据库中原有 2 old_dict = { 3 "#1":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 }, 4 "#2":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 } 5 "#3":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 } 6 } 7 8 # cmdb 新汇报的数据 9 new_dict = { 10 "#1":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 800 }, 11 "#3":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 } 12 "#4":{ 'hostname':c2, 'cpu_count': 2, 'mem_capicity': 80 } 13 } 14 15 #添加：旧数据不存在而新数据有的 new_set-olb_set 16 #删除：新数据中没有，旧数据中存在的 old_set-new_set 17 #更新：旧数据存在，新数据也存在而且内容变更 olb_set&new_set(且value不同)
没事~吐着吐着就习惯了
