Python的set集合浅析

defadd(self,*args,**kwargs):#realsignatureunknown
"""
Addanelementtoaset.

Thishasnoeffectiftheelementisalreadypresent.
"""
pass

#练习1.添加
s1=set()
s1.add("11,22,33")#可以添加字符串和元组，不能添加列表，字典，每次只能添加一个
s1.add("kkkkkkkk")
print(s1)
s1.add("11,22,33")#添加重复字符串不生效
s1.add(("k1","v1"))
print(s1)

#执行结果：
{'11,22,33','kkkkkkkk'}
{'11,22,33','kkkkkkkk',('k1','v1')}
注意：另外一种方法可以添加列表，字典

s2=set([44,55,66,"aaa"])#感觉像是赋值，因为后面被覆盖了
print(s2)
s2=set({"kk":"vv","jj":"oo"})#如果是字典取key
print(s2)

执行结果：
{66,'aaa',44,55}
{'kk','jj'}

defclear(self,*args,**kwargs):#realsignatureunknown
"""Removeallelementsfromthisset."""
pass

#练习2.清空set集合
s1=set()
s1.add("11,22,33")#可以添加字符串和元组，不能添加列表，字典，每次只能添加一个
print(s1)
s1.clear()#清空set集合了
print(s1)

#执行结果：
{'11,22,33'}
set()

defdifference(self,*args,**kwargs):#realsignatureunknown
"""
Returnthedifferenceoftwoormoresetsasanewset.

(i.e.allelementsthatareinthissetbutnottheothers.)
"""
pass

#练习3.比较不同的部分放到新集合
s2=set(["aaa","bbb","ccc","ddd","aaa"])
print(s2)
ret=s2.difference(["aaa","bbb","kkk"])#输出与指定集合不相同的部分放到新集合，无序
print(ret)

执行结果：
{'aaa','ddd','bbb','ccc'}
{'ccc','ddd'}

defdifference_update(self,*args,**kwargs):#realsignatureunknown
"""Removeallelementsofanothersetfromthisset."""
pass

#练习4.更新原有集合，移除相同部分
s2=set(["aaa","bbb","ccc","ddd","aaa"])
print(s2)
ret=s2.difference_update(["aaa","bbb"])#更新原来的集合,移除相同部分，不生成集合
print(s2)
print(ret)#不生成新集合，所以返回了None

#执行结果：
{'ddd','bbb','ccc','aaa'}
{'ccc','ddd'}
None

defdiscard(self,*args,**kwargs):#realsignatureunknown
"""
Removeanelementfromasetifitisamember.

Iftheelementisnotamember,donothing.
"""
pass

#练习5.移除集合里的单个元素
s2=set(["aaa","bbb","ccc","ddd"])
print(s2)
s2.discard("aaa")#移除一个元素，如果元素不存在，donothing
print(s2)

#执行结果：
{'aaa','ccc','bbb','ddd'}
{'ccc','bbb','ddd'}

defintersection(self,*args,**kwargs):#realsignatureunknown
"""
Returntheintersectionoftwosetsasanewset.

(i.e.allelementsthatareinbothsets.)
"""
pass

defintersection_update(self,*args,**kwargs):#realsignatureunknown
"""Updateasetwiththeintersectionofitselfandanother."""
pass

#练习6.取交集
s2=set(["aaa","bbb","ccc","ddd"])
print(s2)
s3=s2.intersection(["aaa"])#原集合不变，取交集，并生成新集合
print(s3)
s2.intersection_update(["aaa"])#更新原集合，移除原集合内容，放进交集
print(s2)

执行结果：
{'ddd','bbb','ccc','aaa'}
{'aaa'}
{'aaa'}

defisdisjoint(self,*args,**kwargs):#realsignatureunknown
"""ReturnTrueiftwosetshaveanullintersection."""
pass

#练习6.判断是否有交集
s2=set(["aaa","bbb","ccc","ddd"])
s3=s2.isdisjoint(["aaa"])#有交集则返回False
s4=s2.isdisjoint(["kkk"])#没交集则返回True
print(s3)
print(s4)

#执行结果：
False
True

defissubset(self,*args,**kwargs):#realsignatureunknown
"""Reportwhetheranothersetcontainsthisset."""
pass

defissuperset(self,*args,**kwargs):#realsignatureunknown
"""Reportwhetherthissetcontainsanotherset."""
pass

#练习7.判断父子集
s2=set(["aaa","bbb","ccc","ddd"])
s3=s2.issubset(["aaa"])#判断这个集合是否包含原集合，即判断原集合是否子集
s4=s2.issuperset(["aaa"])#判断原集合是否包含这个集合，即判断原集合是否父集
print(s3)
print(s4)

#执行结果：
False
True

defpop(self,*args,**kwargs):#realsignatureunknown
"""
Removeandreturnanarbitrarysetelement.
RaisesKeyErrorifthesetisempty.
"""
pass

defremove(self,*args,**kwargs):#realsignatureunknown
"""
Removeanelementfromaset;itmustbeamember.

Iftheelementisnotamember,raiseaKeyError.
"""
pass

#练习8.随机删除和指定删除
s2=set(["aaa","bbb","ccc","ddd"])
s3=s2.pop()#随机删除集合中的一个元素
print(s2)
s2=set(["aaa","bbb","ccc","ddd"])
s4=s2.remove("aaa")#指定删除集合中的一个元素
print(s2)

#执行结果：
{'ccc','ddd','aaa'}
{'bbb','ccc','ddd'}

defsymmetric_difference(self,*args,**kwargs):#realsignatureunknown
"""
Returnthesymmetricdifferenceoftwosetsasanewset.

(i.e.allelementsthatareinexactlyoneofthesets.)
"""
pass

defsymmetric_difference_update(self,*args,**kwargs):#realsignatureunknown
"""Updateasetwiththesymmetricdifferenceofitselfandanother."""
pass

#练习9.差集
s2=set(["aaa","bbb","ccc","ddd"])
s3=s2.symmetric_difference(["aaa","kkk"])#差集，并生成新集合，与difference区别是，循环多了一次，因此差集最好与交集混合用
print(s3)
s4=s2.symmetric_difference_update(["bbb"])#差集，在原集合中改变
print(s2)

#执行结果：
{'ccc','bbb','ddd','kkk'}
{'aaa','ccc','ddd'}

defunion(self,*args,**kwargs):#realsignatureunknown
"""
Returntheunionofsetsasanewset.

(i.e.allelementsthatareineitherset.)
"""
pass

defupdate(self,*args,**kwargs):#realsignatureunknown
"""Updateasetwiththeunionofitselfandothers."""
pass

#练习10.并集和更新
s2=set(["aaa","bbb","ccc","ddd"])
s3=s2.union(["aaa","kkk"])#并集，并生成新集合
print(s3)
s4=s2.update(["bbb","jjj"])#更新，在原集合中改变
print(s2)

#执行结果：
{'ccc','aaa','bbb','ddd','kkk'}
{'ccc','aaa','bbb','ddd','jjj'}