Python基础（四）-集合
2024-08-30 10:24:57
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}
print(id(x))
x.update({'':2})
print(x)
print(id(x))
#执行结果
5584648
{'': 2, '': 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
set工厂函数
练习：
# 数据库中原有
old_dict = {
"#1":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 },
"#2":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 }
"#3":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 }
} # cmdb 新汇报的数据
new_dict = {
"#1":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 800 },
"#3":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 }
"#4":{ 'hostname':c2, 'cpu_count': 2, 'mem_capicity': 80 }
} #添加：旧数据不存在而新数据有的 new_set-olb_set
#删除：新数据中没有，旧数据中存在的 old_set-new_set
#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)
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