python学习实例（6）

阳光穿透心脏的1/2处 2022-05-08 14:03 198阅读 0赞

#=============================
    #6.6 文件系统（File System）
    #=============================
    
    #+++++++++++++++++++++++++++++
    #6.6.3 Python中的文件操作
    #+++++++++++++++++++++++++++++
    
    #<程序：读取文件os.py>
    f = open("./Task1.txt",'r'); fls = f.readlines()
    for line in fls:
        line = line.strip(); print (line)
    f.close()
    
    
    
    #<程序：读取文件os.py，计算并写回>
    f = open("./Task1.txt",'r+'); fls = f.readlines()
    for line in fls:
        line = line.strip(); lstr = line.split()
        if lstr[0] == '3':
            res = 0
            for e in lstr[1:]:
                res+=int(e)
    f.write('\n4 '+str(res)); f.close()
    
    
    #+++++++++++++++++++++++++++++
    #6.6.4 学生实例4.6.3扩展
    #+++++++++++++++++++++++++++++
    
    #<程序：存储考试结果到class1.txt文件>
    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)
    
    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)
    
    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)
    
    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
    
    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)
    
    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)
    
    import random
    CourseDict={}
    StudentDict={}
    setupCourse(CourseDict)
    setupClass(StudentDict)
    SelectCourse(list(StudentDict.values()),list(CourseDict.values()))
    ExamSimulation(list(StudentDict.values()),list(CourseDict.values()))
    
    SaveToFile = ["ID"," ","Name"," ","Credit"," ","GPA","\n"]
    for stu in StudentDict.values():
                    SaveToFile.append(str(stu.StuID))
                    SaveToFile.append(" ")
                    SaveToFile.append(str(stu.name))
                    SaveToFile.append(" ")
                    SaveToFile.append(str(stu.Credit))
                    SaveToFile.append(" ")
                    SaveToFile.append(str(stu.GPA))
                    SaveToFile.append("\n")
    f = open("class1.txt","w")
    f.writelines(SaveToFile)
    f.close()
    
    
    
    
    #<程序：查询文件class1.txt中满足某条件的学生信息>
    def select(path,col,op,val):
    	f = open(path,"r")
    	colNum = 0
    	if col == "ID": colNum = 0
    	elif col == "Name": colNum = 1
    	elif col == "Credit": colNum = 2
    	elif col == "GPA": colNum = 3
    	f.readline()
    	Info = f.readlines()
    	res = []
    	for e in Info:
    		e = e.strip()
    		eList = e.split()
    		if colNum != 1:
    			exp = eList[colNum] + op + val
    		else:
    			exp = "'" + eList[colNum] + "'" + op + "'" + val + "'"
    		if eval(exp):
    			res.append(e)
    	f.close()
    	return res
    for e in select("class1.txt","Credit",">=","15"):
        print (e)
    
    
    
    #<程序：对文件class1.txt中学生进行排序>
    def sort(path,col,direct):	
    #direct表示排序方向，">"为从大到小排序，"<"相反。
    	colNum = 0
    	if col == "Credit": colNum = 2
    	elif col == "GPA": colNum = 3
    	ifrev = False
    	if direct == ">":ifrev = True
    	f = open(path,"r")
    	f.readline()
    	Info = f.readlines()
    	res = []
    	for e in Info:
    		eList = e.split()
    		res.append(eList)
    	res =sorted(res, key=lambda res: res[colNum],reverse=ifrev) 
    #第三个参数为排序方向
    	f.close()
    	return res
    L = [('b',2),('a',1),('c',3),('d',4)]
    print (sorted(L, key=lambda x:x[1]))