python学习实例（4）

╰半夏微凉° 2022-05-08 14:03 202阅读 0赞

#=========================================
    #第四章的python程序
    #=========================================
    
    #=========================================
    #4.1 简洁的Python
    #=========================================
    
    #<程序：Python数组各元素加1>
    arr = [0,1,2,3,4]
    for e in arr:
    	tmp=e+1
    	print (tmp)
    
    #==================================================================================================
    
    #=========================================
    #4.2 Python内置数据结构
    #=========================================
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.2.1 Python基本数据类型
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：产生10-20的随机浮点数>
    import random
    f = random.uniform(10,20)
    print(f)
    
    
    
    #<程序：产生10-20的随机整数>
    import random
    i = random.randint(10,20)
    print(i)
    
    
    
    #<程序：布尔类型例子>
    b = 100<101
    print (b)
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.2.2 列表（list）
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：序列索引>
    L=[1,1.3,"2","China",["I","am","another","list"]]
    print(L[0])
    
    
    
    #<程序：序列加法>
    L1= [1,1.3]
    L2= ["2","China",["I","am","another","list"]]
    L = L1 +L2
    print(L)
    
    
    
    #<程序：字符串专用方法调用>
    L=[1,1.3,"2","China",["I","am","another","list"]]
    L.append("Hello world!")
    print(L)
    
    
    
    #<程序：while循环对列表进行遍历>
    L = [1,3,5,7,9,11]
    mlen = len(L)
    i =0
    while(i<mlen):
        print(L[i]+1)
        i += 1
    
    
    
    #<程序：for循环对列表进行遍历>
    L = [1,3,5,7,9,11]
    for e in L:
        e+=1
        print(e)
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.2.3 再谈字符串
    #+++++++++++++++++++++++++++++++++++++++++
    
    #第一种方式
    S=input("1. Enter 1,2, , , :")#Enter: 1,2,3,4
    L = S.split(sep=',')		#['1','2','3','4']
    X=[]
    for a in L:
        X.append(int(a))
    print("Use split:", X)
    
    
    
    #第二种方式
    S=input("2. Enter 1,2, , , :")#Enter: 1,2,3,4
    L = S.split(sep=',')			#['1','2','3','4']
    L= [int(e) for e in L]
    print("Use split and embedded for:", L)
    
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.2.4 字典（Dictionary）——类似数据库的结构
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：统计字符串中各字符出现次数>
    mstr = "Hello world, I am using Python to program, it is very easy to implement."
    mlist = list(mstr)
    mdict = {}
    for e in mlist:
        if mdict.get(e,-1)==-1:	#还没出现过
            mdict[e]=1
        else:					#出现过
            mdict[e]+=1
    for key,value in mdict.items():
        print (key,value)
    
    
    #练习题4.2.13
    
    #程序1
    d_info1={'XiaoMing':[ 'stu','606866'],'AZhen':[ 'TA','609980']}
    print(d_info1['XiaoMing'])
    print(d_info1['XiaoMing'][1])
    
    
    
    #程序2
    d_info2={'XiaoMing':{ 'role': 'stu','phone':'606866'},
    'AZhen':{ 'role': 'TA','phone':'609980'}}
    print(d_info2['XiaoMing'])
    print(d_info2['XiaoMing']['phone'])
    
    
    
    #练习题4.2.14
    
    #程序1
    di={'fruit':['apple','banana']}
    di['fruit'].append('orange')
    print(di)
    
    
    
    #程序2
    D={'name':'Python','price':40}
    D['price']=70
    print(D)
    del D['price']
    print(D)
    
    
    
    #程序3
    D={'name':'Python','price':40}
    print(D.pop('price'))
    print(D)
    
    
    
    #程序4
    D={'name':'Python','price':40}
    D1={'author':'Dr.Li'}
    D.update(D1)
    print(D)
    
    
    #==================================================================================================
    
    #=========================================
    #4.3 Python赋值语句
    #=========================================
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.3.1 基本赋值语句
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：基本赋值语句>
    x=1; y=2
    k=x+y
    print(k)
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.3.2 序列赋值
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：序列赋值语句>
    a,b=4,5
    print(a,b)
    a,b=(6,7)
    print(a,b)
    a,b="AB"
    print(a,b)
    ((a,b),c)=('AB','CD') #嵌套序列赋值
    print(a,b,c)
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.3.3 扩展序列赋值
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：扩展序列赋值语句>
    i,*j=range(3)
    print(i,j)
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.3.4 多目标赋值
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：多目标赋值语句1>
    i=j=k=3
    print(i,j,k)
    i=i+2 #改变i的值，并不会影响到j, k
    print(i,j,k)
    
    
    
    #<程序：多目标赋值语句2>
    i=j=[] 	#[]表示空的列表，定义i和j都是空列表，i和j指向同一个空的列表地址
    i.append(30)  #向列表i中添加一个元素30，列表j也受到影响
    print(i,j)
    i=[];j=[]
    i.append(30)
    print(i,j)
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.3.5 增强赋值语句
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：增强赋值语句1>
    i=2
    i*=3       #等价于i=i*3
    print(i)
    
    
    
    #<程序：增强赋值语句2>
    L=[1,2]; L1=L; L+=[4,5]
    print(L,L1)
    
    
    
    #<程序：增强赋值语句3>
    L=[1,2]; L1=L; L=L+[4,5]
    print(L,L1)
    
    
    #==================================================================================================
    
    
    #=========================================
    #4.4 Python控制结构
    #=========================================
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.4.1 if语句
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：if语句实现百分制转等级制>
    def if_test(score):
    	if(score>=90):
    		print('Excellent')
    	elif(score>=80):
    		print('Very Good')
    	elif(score>=70):
    		print('Good')
    	elif(score>=60):
    		print('Pass')
    	else:
    		print('Fail')
    if_test(88)
    
    
    
    #<程序：if语句举例—扩展>
    def if_test(score):
        if(score>=90):
            print('Excellent',end=' ')
            if(score>=95):
                print('*')
            else:
                print(' ')
    if_test(98)
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.4.2 While循环语句
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：while循环实现从大到小输出2*x，0<x<=10 >
    x=10
    while x>0:
        print(2*x,end=' ')
        x=x-1
    
    
    
    #<程序：while循环实现从大到小输出2*x，x不是3的倍数>
    x=10
    while x>0:
        if x%3 == 0:
            x=x-1
            continue
        print(2*x,end=' ')
        x=x-1
    
    
    
    #<程序：while循环实现从大到小输出2*x，x第一次为6的倍数时退出循环>
    x=10
    while x>0:
        if x%6 == 0:
            break
        print(2*x,end=' ')
        x=x-1
    
    
    
    #<程序：while循环例子1改进>
    i = 1
    while True:
        print(i,'printing')
        if i==2:
            break
        i=i+1
    
    
    
    #<程序：判断是否为质数>
    b=7
    a=b//2
    while a>1:
        if b%a==0:
            print('b is not prime')
            break
        a=a-1
    else:    #没有执行break，则执行else
        print('b is prime')
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.4.3 for循环语句
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：for的目标<target>变量>
    i=1
    m=[1,2,3,4,5]
    def func():
        x=200
        for x in m:
            print(x);
        print(x);
    func ()
    
    
    
    #<程序：while循环改变列表2>
    words=['cat','window', 'defenestrate']
    for w in words[:]:
        if len(w)>6:
            words.append(w)
    print(words)
    
    
    
    #<程序：使用range遍历列表>
    L=['Python','is','strong']
    for i in range(len(L)):
        print(i,L[i],end=' ')
    
    
    #==================================================================================================
    
    #=========================================
    #4.5 Python函数调用
    #=========================================
        
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.5.1 列表做参数
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：列表的append方法>
    def func(L1):
        L1.append(1)
    L=[2]
    func(L)
    print(L)
    
    
    
    #<程序：加法(+)合并列表>
    def func(L1):
        x=L1+[1]
        print(x,L1)
    L=[2]
    func(L)
    print (L)
    
    
    
    #<程序：列表分片的例子>
    def func(L1):
        x=L1[1:3]
        print(x,L1)
    L=[2,'a',3,'b',4]
    func(L)
    print(L)
    
    
    #<程序: L=X>
    def F0():
         X=[9,9]   #X是局部变量，这个指针在局部栈上，但是[9,9]在外面heap上。
         L.append(8)    #L是全局变量
    X=[1,2,3]
    L=X
    F0()
    print("X=",X,"L=",L)
    
    
    
    #<程序: L=X[:]>
    def F0():
         X=[9,9]   #X 这个指针在局部栈上，但是[9,9]在外面heap上。
         L.append(8)   #L是全局变量
    X=[1,2,3]; L=X[:]		#L是X的全新拷贝
    F0()		#改变L不会改变X
    print("X=",X,"L=",L)
    
    
    
    #<程序: 返回(return)列表>
    def F1():
         L=[3,2,1]	#L是局部变量，而[3,2,1]内容是在栈的外面，heap上
         return(L)   # 传回指针指到[3,2,1]。这个[3,2,1]内容不会随F1结束而消失。
    L=F1()
    print("L=",L)
    
    
    
    #<程序: L做函数参数传递>
    def F2(L):		#参数L是个指针，是存在栈上的局部变量
         L=[2,1]		#L 指向一个全新的内容，和原来的参数L完全分开了。
         return(L)
    def F3(L):		#参数L是个指针，是存在栈上的局部变量
         L.append(1)    #L 指向的是原来的全局内容。会改变全局L
         L[0]=0
    L= [3, 2, 1]
    L=F2(L);print("L=",L)
    F3(L);print("L=",L)
    
    
    
    #<程序: list为参数的递归函数>
    def recursive(L): 
        if L ==[]: return 
        L=L[0:len(L)-1]   # L指向新产生的一个list，和原来的List完全脱钩了
        print("L=",L) 
        recursive(L) 
        print("L:",L) 
        return 
    X=[1,2,3] 
    recursive(X) 
    print("outside  recursive, X=",X)
    
    
    
    #练习题4.5.2
    
    def recursive_2(L): 
        if L ==[]: return 
        print("L=",L) 
        recursive_2(L[0:len(L)-1]) 
        print("L:",L) 
        return 
    X=[1,2,3] 
    recursive_2(X) 
    print("outside  recursive_2, X=",X)
    
    
    #==================================================================================================
    
    #=========================================
    #4.6 Python自定义数据结构
    #=========================================
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.6.2 面向对象基本概念——类(Class)与对象(Object)
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：自定义学生student类，并将该类实例化>
    class student:	 #学生类型：包含成员变量和成员函数
    	def __init__ (self,mname,mnumber):#当新对象object产生时所自动执行的函数
    		self.name = mname				#self代表这个object。名字
    		self.number = mnumber			#ID号码
    		self.Course_Grade = {}			#字典存课程和其分数
    		self.GPA = 0					#平均分数
    	def getInfo(self):
    		print(self.name,self.number)
    XiaoMing = student("XiaoMing","1")		
    #每一个学生是一个object，参数给__init()__
    A_Zhen = student("A_Zhen","2")
    XiaoMing.getInfo()
    A_Zhen.getInfo()
    
    
    #==================================================================================================
    
    #=========================================
    #4.7 基于Python面向对象编程实现数据库功能
    #=========================================
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.7.1 Python面向对象方式实现数据库的学生类
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：扩展后的Student类>
    class student:
    	def __init__ (self,mname,studentID):
    		self.name = mname; self.StuID = studentID;	self.Course_Grade = {};
    		self.Course_ID = []; self.GPA = 0;	self.Credit = 0
    	def selectCourse(self,CourseName,CourseID):
    		self.Course_Grade[CourseID]=0;			#CourseID:0 加入字典
    		self.Course_ID.append(CourseID)			# CourseID 加入列表
    		self.Credit = self.Credit+ CourseDict[CourseID].Credit #总学分数更新
    	def getInfo(self):
    		print("Name:",self.name);print("StudentID",self.StuID);print("Course:")
    		for courseID,grade in self.Course_Grade.items():
    			print(CourseDict[courseID].courseName,grade)
    			print("GPA",self.GPA); 	print("Credit",self.Credit); print("")
    	def TakeExam(self, CourseID):
    		self.Course_Grade[CourseID]=random.randint(50,100)
    		self.calculateGPA()
    	def Grade2GPA(self,grade):
    		if(grade>=90):
    			return 4
    		elif(grade>=80):
    			return 3
    		elif(grade>=70):
    			return 2
    		elif(grade>=60):
    			return 1
    		else:
    			return 0
    	def calculateGPA(self):
    		g = 0;
    		#遍历每一门所修的课程
    		for courseID,grade in self.Course_Grade.items():
    			g = g + self.Grade2GPA(grade)* CourseDict[courseID].Credit
    		self.GPA = round(g/self.Credit,2)
    
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.7.2 Python面向对象方式实现数据库的课程类
    #+++++++++++++++++++++++++++++++++++++++++
    		
    #<程序：课程类>
    class Course:
    	def __init__ (self,cid,mname,CourseCredit,FinalDate):
    		self.courseID = cid
    		self.courseName = mname
    		self.studentID = []
    		self.Credit = CourseCredit
    		self.ExamDate = FinalDate
    	def SelectThisCourse(self,stuID):	#记录谁修了这门课，在studentID列表里
    		self.studentID.append(stuID)
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.7.3 Python创建数据库的学生与课程类组
    #+++++++++++++++++++++++++++++++++++++++++
    		
    #<程序：建立课程信息>
    def setupCourse (CourseDict):	#建立CourseList: list of Course objects
        CourseDict[1]=Course(1,"Introducation to Computer Science",4,1)
        CourseDict[2]=Course(2,"Advanced Mathematics",5,2)
        CourseDict[3]=Course(3,"Python",3,3)
        CourseDict[4]=Course(4,"College English",4,4)
        CourseDict[5]=Course(5,"Linear Algebra",3,5)
    
    
    
    #<程序：建立班级信息>
    def setupClass (StudentDict):    #输入一个空列表
        NameList = ["Aaron","Abraham","Andy","Benson","Bill","Brent","Chris","Daniel",
        "Edward","Evan","Francis","Howard","James","Kenneth","Norma","Ophelia","Pearl",
        "Phoenix","Prima","XiaoMing"] 
        stuid = 1
        for name in NameList:
            StudentDict [stuid]=student(name,stuid)     #student对象的字典
            stuid = stuid + 1
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.7.4 Python实例功能模拟
    #+++++++++++++++++++++++++++++++++++++++++
            
    #<程序：模拟选课>
    def SelectCourse (StudentList, CourseList):
        for stu in StudentList:		#每一个学生修几门课
            CourseNum = random.randint(3,len(CourseList))		#修CourseNum数量的课
            #随机选，返回列表
            CourseIndex = random.sample(range(len(CourseList)), CourseNum)
            for index in CourseIndex:
                stu.selectCourse(CourseList[index].courseName,CourseList[index].Credit)
                CourseList[index].SelectThisCourse(stu.StuID)
    
    
    
    #<程序：模拟考试>
    def ExamSimulation (StudentList, CourseList):
        for day in range(1,6):	#Simulate the date
            for cour in CourseList:
                if(cour.ExamDate==day):	# Hold the exam of course on that day
                    for stuID in cour.studentID:
                        for stu in StudentList:
                            if(stu.StuID == stuID):	#student stuID selected this course
                                stu.TakeExam(cour.courseID)
    
    
    
    #<程序：主程序>
    import random
    CourseDict={}
    StudentDict={}
    setupCourse(CourseDict)
    setupClass(StudentDict)
    SelectCourse(list(StudentDict.values()),list(CourseDict.values()))
    ExamSimulation(list(StudentDict.values()),list(CourseDict.values()))
    for sid,stu in StudentDict.items():
    	stu.getInfo()
    
    
    #==================================================================================================
    
    #=========================================
    #4.8 有趣的小乌龟——Python之绘图
    #=========================================
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.8.2 小乌龟绘制基础图形绘制
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：绘出三条不同的平行线>
    from turtle import *
    def jumpto(x,y):		#移动小乌龟不绘图
            up(); goto(x,y); down()
    reset()			#置小乌龟到原点处
    colorlist = ['red','green','yellow']
    for i in range(3):
            jumpto(-50,50-i*50);width(5*(i+1));
            color(colorlist[i])   #设置小乌龟属性
            forward(100)	#绘图
    s = Screen(); s.exitonclick()
    
    
    
    #<程序：绘出边长为50的正方形>
    from turtle import *
    def jumpto(x,y):
    	up(); goto(x,y); down()
    reset()
    jumpto(-25,-25)
    k=4
    for i in range(k):
    	forward(50)
    	left(360/k)
    s = Screen(); s.exitonclick()
    
    
    #解法1
    
    #<程序：绘出半径为50的圆>
    from turtle import *
    import math
    def jumpto(x,y):
        up(); goto(x,y); down()
    def getStep(r,k):
    	rad = math.radians(90*(1-2/k))
    	return ((2*r)/math.tan(rad))
    def drawCircle(x,y,r,k):
    	S=getStep(r,k)
    	speed(10); jumpto(x,y)	
    	for i in range(k):
    		forward(S)
    		left(360/k)
    reset()
    drawCircle(0,0,50,20)
    s = Screen(); s.exitonclick()
    
    
    #解法1
    
    #<程序：绘出半径为50的圆>
    from turtle import *
    circle(50)
    s = Screen(); s.exitonclick()
    
    
    
    #+++++++++++++++++++++++++++++++++++++++++
    #4.8.3 小乌龟绘制迷宫
    #+++++++++++++++++++++++++++++++++++++++++
    
    #<程序：迷宫输入>
    m=[[1,1,1,0,1,1,1,1,1,1],
       [1,0,0,0,0,0,0,0,1,1],
       [1,0,1,1,1,1,1,0,0,1],
       [1,0,1,0,0,0,0,1,0,1],
       [1,0,1,0,1,1,0,0,0,1],
       [1,0,0,1,1,0,1,0,1,1],
       [1,1,1,1,0,0,0,0,1,1],
       [1,0,0,0,0,1,1,1,0,0],
       [1,0,1,1,0,0,0,0,0,1],
       [1,1,1,1,1,1,1,1,1,1]]
    
    
    
    #<程序：迷宫中的墙与通道绘制>
    from turtle import *
    def jumpto(x,y):
        up(); goto(x,y); down()
    def Access(x,y):
    	jumpto(x,y)
    	for i in range(4):
    		forward(size/6); up(); forward(size/6*4); down();
    		forward(size/6); right(90)
    def Wall(x,y,size):
    	color("red"); jumpto(x,y);
    	for i in range(4):
    		forward(size)
    		right(90)
    	goto(x+size,y-size); jumpto(x,y-size); goto(x+size,y)
    
    
    
    #<程序：小乌龟画迷宫>
    reset(); speed('fast')
    size=40; startX = -len(m)/2*size; startY = len(m)/2*size
    for i in range(0,len(m)):
    	for j in range(0,len(m[i])):
    		if m[i][j]==0:
    			Access(startX+j*size, startY-i*size)
    		else:
    			Wall(startX+j*size, startY-i*size,size)
    s = Screen(); s.exitonclick()   
    
    
    
    #程序练习题4.8.2
    
    #<程序：多个圆形的美丽聚合>
    from turtle import *
    reset()
    speed('fast')
    IN_TIMES = 40
    TIMES = 20
    for i in range(TIMES):
        right(360/TIMES)
        forward(200/TIMES)  #这一步是做什么用的？
        for j in range(IN_TIMES):
            right(360/IN_TIMES)
            forward (400/IN_TIMES)
    write(" Click me to exit", font = ("Courier", 12, "bold") )
    s = Screen()
    s.exitonclick()