【1.16】集合set

python的set和其他语言类似, 是一个无序不重复元素集, 

基本功能包括关系测试和消除重复元素.

 
集合对象还支持union(联合), intersection(交), 

difference(差)和sysmmetric difference(对称差集)等数学运算.


sets 支持 x in set, len(set),和 for x in set。

作为一个无序的集合，sets不记录元素位置或者插入点。

因此，sets不支持 indexing, slicing, 或其它类序列（sequence-like）的操作。

定义： 就是无序 可以hash，不能重复
set创建，或者 大括号{}，元素间使用逗号隔开，这两种方式都可以

b={"abc","zhanshan","yaoming"}
print b
a = set(b)
# 这里的set 中的参数只能是一个，
# 且这一个参数一定要是可以迭代的对象，
# 也就是要是能进行for循环的
# 可以是 str list  元组  字典中默认就是添加key为集合中的元素
# 因为字典默认的循环就是循环key，这个在字典里面就有讲解和说明
# 但是这里有一个奇怪的现象 就是set里面，可以写入集合
print a
# set(['abc', 'zhanshan', 'yaoming'])
# set(['abc', 'zhanshan', 'yaoming'])

a = set("abcd1234")
print a
b = {'a', 'c', 'b', 'd', '1', '3', '2', '4'}
print b
print a==b

# set(['a', 'c', 'b', 'd', '1', '3', '2', '4'])
# set(['a', 'c', 'b', 'd', '1', '3', '2', '4'])
# True

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


1、给集合添加元素

a = set(("abc","zhanshan","yaoming"))
# 这里的set 中的参数只能是一个，
# 且这一个参数一定要是可以迭代的对象，
# 也就是要是能进行for循环的
# 可以是 str list  元组  字典中默认就是添加key为集合中的元素
# 因为字典默认的循环就是循环key，这个在字典里面就有讲解和说明
print a
a.add("kebi")
print a

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

2、清空集合中的元素
将集合中的元素清空

set([])



def copy(self, *args, **kwargs): # real signature unknown
    """ Return a shallow copy of a set. """
    pass

3、复制集合 
将a变量对应的原集合 复制 给另外的变量b


def difference(self, *args, **kwargs): # real signature unknown
    """
    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

4、求两个集合的差  set1-set2  返回 就是在set1 不在 set2的集合

set1=set(['abc', 'kebi', 'zhanshan', 'yaoming'])
set2={"abc","zhanshan","liuxiang"}
print set2
print set1
set3=set1.difference(set2)
print set3
set4=set1-set2
print set4

# set(['abc', 'zhanshan', 'liuxiang'])
# set(['yaoming', 'abc', 'zhanshan', 'kebi'])
# set(['yaoming', 'kebi'])
# set(['yaoming', 'kebi'])

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

5、求两个集合的差，并更新  相当于 set1=set1-set2  

但是写法是

set1=set(['abc', 'kebi', 'zhanshan', 'yaoming'])
set2={"abc","zhanshan","liuxiang"}
print set1
print set2
set3=set1.difference_update(set2)
print set3   #返回set3=None
print set1   #set1自动修改为set1-set2
print set2   #set2 不变

# None
# set(['yaoming', 'kebi'])
# set(['abc', 'zhanshan', 'liuxiang'])

def discard(self, *args, **kwargs): # real signature unknown
    """
    Remove an element from a set if it is a member.
    
    If the element is not a member, do nothing.
    """
    pass
6、删除指定的元素 返回是None

set1=set(['abc', 'kebi', 'zhanshan', 'yaoming'])
set2={"abc","zhanshan","liuxiang"}
print set1
print set2
set3=set1.discard("abc")
set4=set2.discard("liuxiang")
print set1
print set2
print set3
print set4


# set(['yaoming', 'abc', 'zhanshan', 'kebi'])
# set(['abc', 'zhanshan', 'liuxiang'])
# set(['yaoming', 'zhanshan', 'kebi'])
# set(['abc', 'zhanshan'])
# None
# None

def intersection(self, *args, **kwargs): # real signature unknown
    """
    Return the intersection of two or more sets as a new set.
    
    (i.e. elements that are common to all of the sets.)
    """
    pass


7、交集 计算 不改变原来集合的值，返回交集的集合

set1=set(['abc', 'kebi', 'zhanshan', 'yaoming'])
set2={"abc","zhanshan","liuxiang"}
print set1
print set2
set3=set1.intersection(set2)

print set1
print set2
print set3

# set(['yaoming', 'abc', 'zhanshan', 'kebi'])
# set(['abc', 'zhanshan', 'liuxiang'])
# set(['yaoming', 'abc', 'zhanshan', 'kebi'])
# set(['abc', 'zhanshan', 'liuxiang'])
# set(['abc', 'zhanshan'])

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

8、交集，然后修改被交集的集合，让它等于交集  返回结果是 None

set1=set(['abc', 'kebi', 'zhanshan', 'yaoming'])
set2={"abc","zhanshan","liuxiang"}
print set1
print set2
set3=set1.intersection_update(set2)

print set1
print set2
print set3


# set(['yaoming', 'abc', 'zhanshan', 'kebi'])
# set(['abc', 'zhanshan', 'liuxiang'])
# set(['abc', 'zhanshan']) 　　set1   被修改为交集了
# set(['abc', 'zhanshan', 'liuxiang']) set2 不变
# None 返回值 set3

def isdisjoint(self, *args, **kwargs): # real signature unknown
    """ Return True if two sets have a null intersection. """
    pass
9、判断交集是否为空 ，为空就是True　　有交集为False

set1=set(['abc', 'kebi', 'zhanshan', 'yaoming'])
set2={"abc","zhanshan","liuxiang"}
print set1
print set2
set3=set1.isdisjoint(set2)

print set1
print set2
print set3

# set(['yaoming', 'abc', 'zhanshan', 'kebi'])
# set(['abc', 'zhanshan', 'liuxiang'])
# set(['yaoming', 'abc', 'zhanshan', 'kebi'])
# set(['abc', 'zhanshan', 'liuxiang'])  不修改原来集合的值
# False  有交集 返回False

def issubset(self, *args, **kwargs): # real signature unknown
    """ Report whether another set contains this set. """
    pass

10、判断集合 y 能否包含 x  集合 y 是 issubset 的参数  ，判断 x是y的子集？

x = {"a", "b", "c"}

y = {"f", "e", "d", "c", "b", "a"}

z = x.issubset(y)

print(z)

def issuperset(self, *args, **kwargs): # real signature unknown
    """ Report whether this set contains another set. """
    pass
11、判断指定集合是否是被称作集合的子集（10相反）

x = {"f", "e", "d", "c", "b"}

y = {"a", "b", "c"}

z = x.issuperset(y)

print(z)

def pop(self, *args, **kwargs): # real signature unknown
    """
    Remove and return an arbitrary set element.
    Raises KeyError if the set is empty.
    """
    pass
12、删除一个元素 随机删除（其实是删除当前集合中最后一个元素），删除后返回该元素 


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
13、指定移除一个元素 返回None，没有就报错


def symmetric_difference(self, *args, **kwargs): # real signature unknown
    """
    Return the symmetric difference of two sets as a new set.
    
    (i.e. all elements that are in exactly one of the sets.)
    """
    pass

14、返回两个集合中不重复的元素集合，即会移除两个集合中都存在的元素。
set1 union set2 - set1 intersection set2 
就是并集  减去 交集


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

15、移除当前集合中在另外一个指定集合相同的元素，并将另外一个指定集合中不同的元素插入到当前集合中。

set1=set1 union set2 - set1 intersection set2 
set1=就是并集  减去 交集

def union(self, *args, **kwargs): # real signature unknown
    """
    Return the union of sets as a new set.
    
    (i.e. all elements that are in either set.)
    """

    pass
16、并 集  去重
包含了所有集合的元素，重复的元素只会出现一次。

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

17、可以添加新的元素或集合到当前集合中，如果添加的元素在集合中已存在，则该元素只会出现一次，重复的会忽略。

py3里面的 set 方法：

set.add(                          set.issubset(
set.clear(                        set.issuperset(
set.copy(                         set.mro(
set.difference(                   set.pop(
set.difference_update(            set.remove(
set.discard(                      set.symmetric_difference(
set.intersection(                 set.symmetric_difference_update(
set.intersection_update(          set.union(
set.isdisjoint(                   set.update(