一、什么是集合
Python内置数据结构之一- 与列表，字典一样都属于可变序列
- 集合是没有
value的字典
- 集合中的元素是无序的，元素不可以重复
1.集合操作符
| 操作符的运算 |
描述 |
S-T |
返回一个新集合，包括在集合S中但不会在集合T中 |
S&T |
返回一个新集合，包括同时在集合S和T中的元素 |
S^T |
返回一个新集合，包括S和T中的非共同元素 |
| `S\ |
T` |
返回一个新集合，包括集合S和T中的所有元素 |
2.常用集合操作函数或方法
| 函数或方法 |
描述 |
S.add(x) |
如果数据项x不在S中，将x增加到S |
S.remove(x) |
如果x集合在S中，移除该元素；不在则产生KeyError异常 |
S.clear() |
移除S中的数据项 |
len(S) |
返回集合S的元素个数 |
x in S |
如果x是s的元素，返回True；否则返回False |
x not in S |
如果x是s的元素，返回True；否则返回False |
3.内置数据结构set源码
Python内置数据结构集合类class set(object)源码解析：
class set(object): # set类
"""
set() ->新的空集合对象
set (iterable) ->新设置对象
构建独特元素的无序集合。
"""
def add(self, *args, **kwargs): # real signature unknown
"""
向集合中添加一个元素。
如果该元素已经存在，则不会产生任何影响。
"""
pass
def clear(self, *args, **kwargs): # real signature unknown
""" 从这个集合中删除所有元素。 """
pass
def copy(self, *args, **kwargs): # real signature unknown
""" Return a shallow copy of a set.
返回集合的浅副本。
"""
pass
def difference(self, *args, **kwargs): # real signature unknown
"""
返回两个或多个集合的差值作为新集合。
(即所有在这个集合中的元素，而不是其他集合中的元素。)
"""
pass
def difference_update(self, *args, **kwargs): # real signature unknown
""" 从这个集合中删除另一个集合的所有元素 """
pass
def discard(self, *args, **kwargs): # real signature unknown
"""
从集合中移除一个元素，如果它是成员。
如果元素不是成员，则不执行任何操作。
"""
pass
def intersection(self, *args, **kwargs): # real signature unknown
"""
返回两个集合的交集作为新集合。
(即两个集合中的所有元素。)
"""
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
""" 报告另一个集合是否包含此集合。 """
pass
def issuperset(self, *args, **kwargs): # real signature unknown
""" 报告此集合是否包含另一个集合。 """
pass
def pop(self, *args, **kwargs): # real signature unknown
"""
删除并返回任意的set元素。
如果该集合为空则引发KeyError。
"""
pass
def remove(self, *args, **kwargs): # real signature unknown
"""
从集合中移除一个元素;它必须是成员。
如果元素不是成员，则引发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
""" 使用自身和其他集合的并集更新集合。 """
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
二、集合的创建方式
1. 使用 {}
s = {1, 2, 3, 4, 5, 6, 6}
print(s)
# {1, 2, 3, 4, 5, 6}
2. 使用内置函数 set()
s1 = set(range(1, 7))
print(s1)
# {1, 2, 3, 4, 5, 6}
print(set('python'))
# {'p', 'h', 'n', 'o', 't', 'y'}
三、集合的相关操作
1.集合元素的判断操作
| 操作函数 |
描述 |
a in s |
如果a是s的元素，返回True；否则返回False |
a not in s |
如果 a不是s的元素，返回True；否则返回False |
# 判断元素是否在集合中
s = {10, 20, 30, 40, 50, 100}
print(10 in s) # True
print(10 not in s) # False
2.集合的新增操作
# 集合元素的新增操作
s = {10, 20, 30, 40, 50, 100}
s.add(80) # 添加一个元素
print(s)
# {100, 40, 10, 80, 50, 20, 30}
s.update({66, 77, 88}) # 添加多个元素(一次至少添加一个元素 )
print(s)
# {66, 100, 40, 10, 77, 80, 50, 20, 88, 30}
s.update((11, 22, 33))
print(s)
# {33, 66, 100, 40, 10, 11, 77, 80, 50, 20, 22, 88, 30}
3.集合的删除操作
# 集合元素的删除操作
# 1.调用remove方法，一次删除一个指定元素，元素不存在抛异常
s.remove(100)
print(s)
# {33, 66, 40, 10, 11, 77, 80, 50, 20, 22, 88, 30}
# 2.调用discard方法，一次删除一个指定元素，元素不存在不抛异常
s.discard(300)
print(s)
# {33, 66, 40, 10, 11, 77, 80, 50, 20, 22, 88, 30}
# 3.调用pop方法，一次只删除一个任意元素
s.pop()
print(s)
# {66, 40, 10, 11, 77, 80, 50, 20, 22, 88, 30}
# 4.调用clear方法,清空集合
s.clear()
print(s)
# set()
