python学习实例（6）

#=============================
#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 = 0for 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 = 0def 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 4elif(grade>=80):return 3elif(grade>=70):return 2elif(grade>=60):return 1else:return 0def 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].Creditself.GPA = round(g/self.Credit,2)class Course:def __init__ (self,cid,mname,CourseCredit,FinalDate):self.courseID = cidself.courseName = mnameself.studentID = []self.Credit = CourseCreditself.ExamDate = FinalDatedef 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 objectsCourseDict[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 = 1for name in NameList:StudentDict [stuid]=student(name,stuid)     #student对象的字典stuid = stuid + 1def 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 datefor cour in CourseList:if(cour.ExamDate==day):  # Hold the exam of course on that dayfor stuID in cour.studentID:for stu in StudentList:if(stu.StuID == stuID):   #student stuID selected this coursestu.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 = 0if col == "ID": colNum = 0elif col == "Name": colNum = 1elif col == "Credit": colNum = 2elif col == "GPA": colNum = 3f.readline()Info = f.readlines()res = []for e in Info:e = e.strip()eList = e.split()if colNum != 1:exp = eList[colNum] + op + valelse: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 = 0if col == "Credit": colNum = 2elif col == "GPA": colNum = 3ifrev = Falseif direct == ">":ifrev = Truef = 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]))

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