《Python语言程序设计》课件-第四章（中英文课件）

Python语言程序设计【列表基础】PythonLanguageProgramming[ListBasics]知识点【访问列表中的值】1234aList=['Deris','Weng',1,2]

bList=[1,2,3,4,5,6,7]

print("aList[0]:",aList[0])

print("bList[1:5]:",bList[1:5])【例】使用下标索引来访问列表aList[0]:DerisbList[1:5]:[2,3,4,5]输出结果：KnowledgePoints[Accessingvaluesinthelist]1234aList=['Deris','Weng',1,2]

bList=[1,2,3,4,5,6,7]

print("aList[0]:",aList[0])

print("bList[1:5]:",bList[1:5])[Example]UsingasubscriptindextoaccessalistaList[0]:DerisbList[1:5]:[2,3,4,5]Outputresult：知识点【列表的更新】1234aList=['Deris','Weng',1,2]

print("第三个元素为:",aList[2])

aList[2]=3

print("更新后的第三个元素为:",aList[2])【例】列表的更新第三个元素为:1更新后的第三个元素为:3输出结果：[Updatestothelist]1234aList=['Deris','Weng',1,2]

Print("Thethirdelementis:",aList[2])

aList[2]=3

Print("Thethirdupdatedelementis:",aList[2])[Example]UpdatestothelistThethirdelementis:1Theupdatedthirdelementis:3KnowledgePointsOutputresult：知识点【向列表指定位置插入元素】123aList=['Deris','Weng',1,2]

aList.insert(2,'Happy')#使用insert向索引2的位置插入元素‘黄金分割’

print("aList结果为:",aList)#列表中有5个元素【例】向列表插入元素aList结果为:['Deris','Weng','Happy',1,2]输出结果：[Insertanelementintothelistatthespecifiedposition]123aList=['Deris','Weng',1,2]

AList.insert(2,'Happy')#Useinserttoinserttheelement'GoldenSection'intothepositionofindex2

Print("aListresultsare:",aList)#Thereare5elementsinthelist[Example]InsertingelementsintoalistTheaListresultis:['Deris','Weng','Happy',1,2]KnowledgePointsOutputresult：知识点【删除或清空列表中的记录】1234aList=['Deris','Weng',1,2]

print("删除前的列表:",aList)

delaList[2]

print("删除第三个元素后的列表:",aList)【例】利用del语句删除列表中的元素删除前的列表:['Deris','Weng',1,2]删除第三个元素后的列表:['Deris','Weng',2]输出结果：[Deleteoremptyrecordsinthelist]1234aList=['Deris','Weng',1,2]

Print("Listbeforedeletion:",aList)

delaList[2]

Print("Listafterdeletingthethirdelement:",aList)[Example]DeleteelementsinthelistwithdelstatementListbeforedeletion:['Deris','Weng',1,2]Listafterdeletingthethirdelement:['Deris','Weng',2]KnowledgePointsOutputresult：知识点【删除或清空列表中的记录】123456aList=['Deris','Weng',1,2]

#列表本身不包含数据，而是包含变量：aList[0]到aList[3]

first=aList[0]#拷贝列表，创建新的变量引用，而不是数据对象的复制。

delaList[0]#del删除的是变量，而不是数据。

print(aList)

print(first)【例】del语句作用在变量上，而不是数据对象上['Weng',1,2]Deris输出结果：pop方法删除列表中的元素123456aList=['Deris','Weng',1,2]

#Thelistitselfdoesnotcontaindata,butcontainsvariables:aList[0]toaList[3]

first=aList[0]#Copythelistandcreateanewvariablereferenceinsteadofcopyingdataobjects.

delaList[0]#deldeletesvariables,notdata.

print(aList)

print(first)[Example]delstatementsactonvariables,notdataobjects['Weng',1,2]DerisThepopmethoddeletestheelementsinthelist[Deleteoremptyrecordsinthelist]KnowledgePointsOutputresult：知识点【遍历列表、二级索引】123aList=['Deris','Weng',1,2]

foriinaList:

print(i)【例】列表的遍历DerisWeng12输出结果：[Traversinglists,secondaryindexes]123aList=['Deris','Weng',1,2]

foriinaList:

print(i)[Example]IterationofalistDerisWeng12KnowledgePointsOutputresult：知识点【遍历列表、二级索引】12aList=['Deris','Weng',[1,2,3]]

print(aList[2][0])【例】列表的二级索引1输出结果：12aList=['Deris','Weng',[1,2,3]]

print(aList[2][0])[Example]Secondaryindexofalist1[Traversinglists,secondaryindexes]KnowledgePointsOutputresult：Python语言程序设计【索引的使用+元素数量+列表运算符】PythonLanguageProgramming[Useofindexes+numberofelements+listoperators]索引俗称下标。索引值从0开始，直到长度减1位置（例如对10个元素的列表，最大的索引值为［9］）。

知识点【索引的使用】12aList=[1,2,3,4,5,6,7]

print("aList[3]:",aList[3])【例】使用下标索引来访问列表aList[3]:4输出结果：IndexCommonlyknownassubscripts.Theindexvaluestartsfrom0andgoestothelengthminus1position(e.g.foralistof10elements,themaximumindexvalueis[9]).Forexample,foralistof10elements,themaximumindexvalueis[9])KnowledgePoints[UseofIndexes]12aList=[1,2,3,4,5,6,7]

print("aList[3]:",aList[3])[Example]UsingasubscriptindextoaccessalistaList[3]:4Outputresult：知识点【索引的使用】123x=[1,2,3,4,5,6]

print(x[6])#最大的索引值

print(x[-7])#最小的索引值【例】索引越界Traceback(mostrecentcalllast):File"indexError.py",line3,in<module>print(x[6])IndexError:listindexoutofrange输出结果：123x=[1,2,3,4,5,6]

print(x[6])#Maximumindexvalue

print(x[-7])#Minimumindexvalue[Example]IndexoutofboundsTraceback(mostrecentcalllast):File"indexError.py",line3,in<module>print(x[6])IndexError:listindexoutofrangeKnowledgePoints[UseofIndexes]Outputresult：函数len()求集合中的元素数量知识点【求元素数量】1234x=[1,2,3,4,5,6]

y=[]

print(len(x))

print(len(y))【例】函数len()60输出结果：Functionlen()tofindthenumberofelementsintheset[Numberofelementstobefound]1234x=[1,2,3,4,5,6]

y=[]

print(len(x))

print(len(y))[Example]Functionlen()60KnowledgePointsOutputresult：

+

和

*

的操作符+号用于组合列表，*号用于重复列表知识点【列表运算符】12345print([1,2,3,4]+[5,6])#列表的拼接

print(5in[1,2,3,4,5,6])#元素是否存在于列表中

print(['Weng']*3)#列表的重复倍增

forxin[1,2,3]:#列表的迭代

print(x,end="")【例】列表运算符[1,2,3,4,5,6]True['Weng','Weng','Weng']123输出结果：

+and*operatorsThe+signisusedforcombininglists,the*signisusedforrepeatinglists[Listoperators]12345print([1,2,3,4]+[5,6])#Splicingoflists

print(5in[1,2,3,4,5,6])#Whethertheelementexistsinthelist

print(['Weng']*3)#Duplicatemultiplicationofthelist

forxin[1,2,3]:#Iterationoflist

print(x,end="")[Example]Thelistoperator[1,2,3,4,5,6]True['Weng','Weng','Weng']123Outputresult：KnowledgePointsPython语言程序设计【列表函数&方法】PythonLanguageProgrammingListFunctions&Methods知识点【列表函数】1.列表函数函数描述len(list)计算列表元素个数max(list)返回列表元素最大值min(list)返回列表元素最小值list(seq)将元组转换为列表12345a=['Hello','Deris','Weng']

n=[1,2,3]

print(len(a))

print(max(a))

print(min(n))【例】列表函数的使用3Weng1输出结果：KnowledgePoints[ListFunctions]1.thelistfunctionfunctionDescriptionlen(list)countsthenumberofelementsinthelistmax(list)Returnsthemaximumvalueofthelistelementmin(list)Returnstheminimumvalueofthelistelementlist(seq)Convertingtuplestolists12345a=['Hello','Deris','Weng']

n=[1,2,3]

print(len(a))

print(max(a))

print(min(n))[Example]Theuseofthelistfunction3Weng1Outputresult：知识点【列表函数】1234a=['Hello','Deris','Weng']

n=[1,2,3]

x=[a,n]

print(min(x))【例】列表函数的错误使用Traceback(mostrecentcalllast):File"ListError.py",line4,in<module>print(min(x))TypeError:'<'notsupportedbetweeninstancesof'int'and'str'输出结果：1234a=['Hello','Deris','Weng']

n=[1,2,3]

x=[a,n]

print(min(x))[Example]MisuseofthelistfunctionTraceback(mostrecentcalllast):File"ListError.py",line4,in<module>print(min(x))TypeError:'<'notsupportedbetweeninstancesof'int'and'str'KnowledgePoints[ListFunctions]Outputresult：知识点【列表方法】2.列表方法方法描述list.append(obj)在列表末尾添加新的对象list.count(obj)统计某个元素在列表中出现的次数list.extend(seq)在列表末尾一次性追加另一个序列中的多个值（用新列表扩展原来的列表）list.index(obj)从列表中找出某个值第一个匹配项的索引位置list.insert(index,obj)将对象插入列表list.pop(obj=list[-1])移除列表中的一个元素（默认最后一个元素），并且返回该元素的值list.remove(obj)移除列表中某个值的第一个匹配项list.reverse()反向列表中元素[Listmethod]2.ThetabularapproachMethodsDescriptionlist.append(obj)Addsanewobjecttotheendofthelistlist.count(obj)countsthenumberoftimesanelementappearsinthelistlist.extend(seq)Appendmultiplevaluesfromanothersequenceatoncetotheendofthelist(extendstheoriginallistwithanewlist)list.index(obj)Findstheindexpositionofthefirstmatchofavaluefromthelistlist.insert(index,obj)Inserttheobjectintothelistlist.pop(obj=list[-1])Removesanelementfromthelist(defaultstothelastelement)andreturnsthevalueofthatelementlist.remove(obj)removesthefirstmatchofavalueinthelistlist.reverse()elementsinthereverselistKnowledgePoints知识点【列表方法】方法描述list.sort([func])对原列表进行排序list.clear()清空列表list.copy()复制列表list.sort([func])对原列表进行排序12345a=['Hello','Deris','Weng']

a.append('Happy')

print(a)

a.reverse()

print(a)【例】列表方法的使用['Hello','Deris','Weng','Happy']['Happy','Weng','Deris','Hello']输出结果：MethodsDescriptionlist.sort([func])Sortingtheoriginallistlist.clear()Emptythelistlist.copy()Copythelistlist.sort([func])Sortingtheoriginallist12345a=['Hello','Deris','Weng']

a.append('Happy')

print(a)

a.reverse()

print(a)[Example]Theuseofthelistmethod['Hello','Deris','Weng','Happy']['Happy','Weng','Deris','Hello'][Listmethod]KnowledgePointsOutputresult：Python语言程序设计【元组基础】PythonLanguageProgramming[TupleBasics]知识点【声明元组】1234tup1=(50)

print(type(tup1))#不加逗号，类型为整型

tup1=(50,)

print(type(tup1))#加上逗号，类型为元组【例】只包含一个元素的元组<class'int'><class'tuple'>输出结果：创建空元组tup1=()KnowledgePoints[declarationtuple]1234tup1=(50)

print(type(tup1))#Withoutcomma,thetypeisinteger

tup1=(50,)

print(type(tup1))#Addacomma,andthetypeistuple[Example]Atuplecontainingonlyoneelement<class'int'><class'tuple'>Creatinganemptytupletup1=()Outputresult：知识点【访问元组】1234tup1=('Deris','Weng',1,2)

tup2=(1,2,3,4,5,6,7)

print("tup1[0]:",tup1[0])

print("tup2[1:5]:",tup2[1:5])【例】访问元组tup1[0]:Deristup2[1:5]:(2,3,4,5)输出结果：[Accesstuple]1234tup1=('Deris','Weng',1,2)

tup2=(1,2,3,4,5,6,7)

print("tup1[0]:",tup1[0])

print("tup2[1:5]:",tup2[1:5])[Example]Accessingthetupletup1[0]:Deristup2[1:5]:(2,3,4,5)KnowledgePointsOutputresult：知识点【修改元组】1234tup1=(12,34.56);

tup2=('abc','xyz')

tup3=tup1+tup2;

print(tup3)【例】修改元组(12,34.56,'abc','xyz')输出结果：123tup1=(12,34.56)

#以下修改元组元素操作是非法的。

tup1[0]=100【例】非法访问元组Traceback(mostrecentcalllast):File"tupError.py",line3,in<module>tup1[0]=100TypeError:'tuple'objectdoesnotsupportitemassignment输出结果：元组自身不能修改[Modifytuple]1234tup1=(12,34.56);

tup2=('abc','xyz')

tup3=tup1+tup2;

print(tup3)[Example]Modifythetuple(12,34.56,'abc','xyz')123tup1=(12,34.56)

#Thefollowingtupleelementmodificationoperationsareillegal.

tup1[0]=100[Example]IllegalaccesstotupleTraceback(mostrecentcalllast):File"tupError.py",line3,in<module>tup1[0]=100TypeError:'tuple'objectdoesnotsupportitemassignmentThetupleitselfcannotbemodifiedKnowledgePointsOutputresult：Outputresult：知识点【删除元组】12345tup=('Deris','Weng',1,2)

print(tup)

deltup;

print("删除后的元组tup:")

print(tup)【例】元组中的元素不允许删除，只可删除整个元组Traceback(mostrecentcalllast):('Deris','Weng',1,2)File"C:/delTup.py",line5,in<module>print(tup)NameError:name'tup'isnotdefined删除后的元组tup:输出结果：[Deletetuple]12345tup=('Deris','Weng',1,2)

print(tup)

deltup;

print("Deletedtupletup:")

print(tup)[Example]Theelementsinthetuplearenotallowedtobedeleted,onlythewholetuplecanbedeletedTraceback(mostrecentcalllast):('Deris','Weng',1,2)File"C:/delTup.py",line5,in<module>print(tup)NameError:name'tup'isnotdefinedDeletedtupletup:KnowledgePointsOutputresult：元组的特点正好可以“弥补”Python没有常量的“遗憾”，程序中不需要修改的数据都可以声明在元组中。问题:为什么要设计元组？提问【元组基础】Thecharacteristicsoftuplescanjust"makeup"the"regret"thatPythondoesnothaveconstants.Datathatdoesnotneedtobemodifiedintheprogramcanbedeclaredintuples.Question:Whydesigntuples?Askaquestion[TupleBasics]Python语言程序设计【元组运算符+索引与截取+内置函数与方法】PythonLanguageProgramming[TupleOperators+IndexingandIntercepting+Built-inFunctionsandMethods]

+

和

*

的操作符+号用于组合，*号用于重复知识点【元组运算符】12345print(len((1,2,3)))#计算元组元素个数

print((1,2,3,4)+(5,6))#元组的拼接

print(5in(1,2,3,4,5,6))#元素是否存在于元组中

forxin(1,2,3):#元组的迭代

print(x,end="")【例】元组运算符3(1,2,3,4,5,6)True123输出结果：

+and*operatorsThe+signisforcombinations,the*signisforrepetitionsKnowledgePoints[Tupleoperator]12345print(len((1,2,3)))#Calculatethenumberoftupleelements

Print((1,2,3,4)+(5,6))#Splicingoftuples

print(5in(1,2,3,4,5,6))#Whethertheelementexistsinthetuple

forxin(1,2,3):#Iterationoftuples

print(x,end="")[Example]Thetupleoperator3(1,2,3,4,5,6)True123Outputresult：知识点【元组运算符】12print(('Happy！',)*3)#有逗号(,)的情况下实现元组的重复倍增

print(('Happy！')*3)#没有逗号(,)，不认为是元组。【例】元组的使用('Happy！','Happy！','Happy！')Happy！Happy！Happy！输出结果：12print(('Happy！',)*3)#Repeatmultiplicationoftupleswithcommas(,)

print(('Happy！')*3)#Thereisnocomma(,)anditisnotconsideredasatuple.[Example]Theuseoftuples('Happy！','Happy！','Happy！')Happy！Happy！Happy！KnowledgePoints[Tupleoperator]Outputresult：知识点【元组索引与截取】1234Tup=('Deris','Happy','Weng')

print(Tup[2])#读取第三个元素

print(Tup[-2])#反向读取；读取倒数第二个元素

print(Tup[1:])#截取元素，从第二个开始后的所有元素【例】索引与截取WengHappy('Happy','Weng')输出结果：KnowledgePoints[TupleIndexingandInterception]1234Tup=('Deris','Happy','Weng')

print(Tup[2])#Readthethirdelement

print(Tup[-2])#Reversereading;Readthepenultimateelement

print(Tup[1:])#Interceptelements,allelementsafterthesecondone[Example]IndexingandInterceptionWengHappy('Happy','Weng')Outputresult：课后练习【元组截取与拼接】问题:

tup1=（1,2,3,4,5,6,7）print("tup1[0]:",tup1[0])print("tup1[1:5]:",tup1[1:5])结果分别是什么？After-schoolexercises[Tupleinterceptionandsplicing]Question:tup1=（1,2,3,4,5,6,7）print("tup1[0]:",tup1[0])print("tup1[1:5]:",tup1[1:5])Whatweretheresultsrespectively?课后练习【元组截取与拼接】Python表达式结果描述len((1,2,3))长度(1,2,3)+(4,5,6)组合('Hi!',)*4重复3in(1,2,3)元素是否存在于列表中3(1,2,3,4,5,6)('Hi!','Hi