Python Learning--tuples, dictionaries, collections

Meta-group

Function: To store multiple values, the tuple is immutable (can be used as a dictionary key) for the list to read,

Order of

Definition: Age=tuple (11,22,33,44, ' Lgh ') of any type of value separated by commas within ()

1. Priority operations:

　　

value by index age= (11,22,33)Print(age[1]) Slice age= (11,22,33)Print(Age[0:2]) Length age= (11,22,33,44)Print(Len (age)) member Operation age= (11,22,33,44,55,66,77)if33inchAge :Print(True)if50 not inchAge :Print(False) Loop age= (11,22,33,44,55,66) forIinchAge :Print(i)

Dictionary

Function: Record multiple values, each corresponding to the key used to describe the role of value

How to define: separate multiple key:value with commas within {}, where value can be any type, key must be immutable, and usually str type

1. Prioritized operations and built-in methods

　　

1, press key to access the value: can save the preferred dic={'name':'Egon'}Print(dic['name']) dic['name']='Egon'Print(DIC)Print(DIC) dic[' Age']=18Print(DIC) L=['a','b']l[0]='A'l[2]='C'2, Length lendic={'name':'Egon',' Age': 18,'name':'EGON','name':'XXXX'}Print(DIC)Print(Len (DIC))3. Member operations in and notinch: The dictionary member operation is judged by the Keydic={'name':'Egon',' Age': 18,}Print(18inchdic)Print(' Age' inchdic)4, remove dic={'name':'Egon',' Age': 18,} genericdeldic['name']Print(DIC)deldic['XXX']##key不存在则报错Res=dic.pop (' Age')#deletes the value corresponding to key and returns the valuePrint(DIC)Print(RES)#Dic.pop ('XXX')#error If key does not existRes=Dic.popitem ()Print(DIC)Print(RES)5, key keys (), value values (), key value pairs items ()6, cyclic dic={'name':'Egon',' Age':' -','Sex':'male'} forKinchDic.keys ():Print(K,dic[k]) forKinchDIC:Print(K,dic[k]) forVinchdic.values ():Print(v) forKvinchDic.items ():Print(k,v) dic={'name':'Egon',' Age':' -','Sex':'male'}v=dic.get ('name')#this way, even if key does not exist, it will not error. return NonePrint(v)

Collection

　　Purpose: Relational operation, de-weight

How to define: separate elements with commas within {}

Note: 1. There are no duplicate elements in the collection

2. The elements of the collection must be immutable types

1. Common operation and built-in methods:

　　

stus_linux={'Alex','Egon','Zhangquan Egg','li Tie Egg','Oldboy'}stus_python={'li er ya','wxx','Liudehua','Alex','Egon'enroll both Linux and Python students: intersectionPrint(Stus_linux &Stus_python)Print(Stus_linux.intersection (Stus_python)) All students: the collectionPrint(Stus_linux |Stus_python)Print(Stus_linux.union (Stus_python)) only registered Linux, not registered python: Difference setPrint(Stus_linux-Stus_python)Print(Stus_linux.difference (Stus_python))Print(Stus_python-stus_linux)Print(Stus_python.difference (stus_linux)) The name of the student who has not enrolled in two courses: cross-complement setPrint(stus_linux ^Stus_python)Print(Stus_linux.symmetric_difference (Stus_python))

2. Prioritize operations

　　　

length Len member operation in and notinchView S1={1,'a','b','C','D'} forIteminchS1:Print(item) add S1={'a','b','C'}#S1.add () # Add one value at a timeS1.add ((4)Print(S1) s1.update ({3,4,5})#add multiple values at oncePrint(S1) Delete S1.discard ()## When the deleted element does not exist, it will not be an errorS1.discard (4)Print(S1) s1.remove ()#when the deleted element does not exist, an errorS1.remove (4) S1.pop ()#take a random element.res=S1.pop ()Print(S1)Print(RES)

Python Learning--tuples, dictionaries, collections