基础数据类型-set

Set是无序不重复元素的序列，基本功能是删除重复元素和测试成员关系，

创建一个集合可以用set()或者({}),但是创建一个空集合只能用set():

s1 = set()
print("s1 is", type(s1))
s2 = ({1, 2, 3})
print("s2 is ", type(s2))
s3 = ({})
print("s3 is", type(s3))

s1 is <class 'set'>
s2 is  <class 'set'>
s3 is <class 'dict'>

View Result

功能，删除序列里重复元素，测试成员关系，集合运算：

 #删除序列里重复元素
 fruits1 = set({"Apple", "Orange", "Pear", "Apple"})
 print("fruits1:", fruits1)

 #成员测试
 if 'Pear' in fruits1:
     print("Pear is in set")
 else:
     print("Pear is not in set")

 #成员运算
 fruits2 = set({"Apple", "Banana", "Strawberry"})
 print(fruits1 - fruits2) #在fruits1中但不再fruits2中
 print(fruits1 | fruits2) #在fruits1或fruits2中
 print(fruits1 & fruits2) #在fruits1且在fruits2中
 print(fruits1 ^ fruits2) #在fruits1或fruits2中，但不同时在两个集合中

Code

 fruits1: {'Apple', 'Orange', 'Pear'}
 Pear is in set
 {'Orange', 'Pear'}
 {'Apple', 'Orange', 'Strawberry', 'Banana', 'Pear'}
 {'Apple'}
 {'Strawberry', 'Banana', 'Orange', 'Pear'}

Result

Set常用方法有add(), difference(),intersection()等:

 #set常用方法
 fruits2.add("Watermelon")
 print("fruits2:", fruits2)
 print("Fruits in fruits2 but not in fruits1 are:", fruits2.difference(fruits1)) #fruits2中有fruits1中没有
 print("Fruits in fruits1 but not in fruits2 are:", fruits1.difference(fruits2)) #fruits1中有fruits2中没有
 print("Fruits in fruits1 and fruits2 are:", fruits2.intersection(fruits1)) #fruits1,fruits2的交集

Code

 fruits2: {'Strawberry', 'Banana', 'Apple', 'Watermelon'}
 Fruits in fruits2 but not in fruits1 are: {'Strawberry', 'Banana', 'Watermelon'}
 Fruits in fruits1 but not in fruits2 are: {'Pear', 'Orange'}
 Fruits in fruits1 and fruits2 are: {'Apple'}

Result

Set类的定义-其他不常用方法查询：

 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
         """
         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
         """
         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
         """
         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
         """ Report whether another set contains this set. """
         pass

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

Class Set