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 = 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]))
  
 

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原文链接：fantianzuo.blog.csdn.net/article/details/83025226