Sorting a class of students? class Student(object): def __init__(self, lastname, firstname, testscore, labscore): self.lastname = lastname self.firstname = firstname self.testscore = testscore self.labscore = labscore liststu = [Student("baker","tom",132,88), Student("abbey","steven",122,96), Student("lawrence","sarah",144,85), Student("miller","john",132,92), Student("jones","tina",128,94)]

Sorting on Last name: def sortstudentslname(liststu): for i in range(len(liststu)): smallstudent = liststu[i].lastname smallindex = i for j in range(i+1,len(liststu)): if liststu[j].lastname < smallstudent: smallstudent = liststu[j].lastname smallindex = j temp = liststu[i] liststu[i] = liststu[smallindex] liststu[smallindex] = temp return(liststu)

class Student(object): def __init__(self, lastname, firstname, testscore, labscore): self.lastname = lastname self.firstname = firstname self.testscore = testscore self.labscore = labscore def __str__(self): strvar = "Student ( \n“ + "Lastname: " + self.lastname + "\n" strvar += "Firstname: " + self.firstname + "\n" strvar += "Testscore: " + str(self.testscore)+"\n“+"Labscore: "+str(self.labscore)+"\n" strvar += ")\n\n" return(strvar) liststu = [Student("baker","tom",132,88), Student("abbey","steven",122,96), Student("lawrence","sarah",144,85), Student("miller","john",132,92), Student("jones","tina",128,94)] def sortstudentslname(liststu): for i in range(len(liststu)): smallstudent = liststu[i].lastname smallindex = i for j in range(i+1,len(liststu)): if liststu[j].lastname < smallstudent: smallstudent = liststu[j].lastname smallindex = j temp = liststu[i] liststu[i] = liststu[smallindex] liststu[smallindex] = temp return(liststu) def printstu(liststu): for i in range(len(liststu)): print liststu[i] printstu(liststu) sortstudentslname(liststu) printstu(liststu)

Operator Overloading That was a lot of work! Easier way??? Of course! Writing our own definition of what an operator should do – E.g., defining student1<student2 to mean: Does student1’s last name property come before student 2’s last name property?

In class: class Student(object): def __init__(self, lastname, firstname, testscore, labscore): self.lastname = lastname self.firstname = firstname self.testscore = testscore self.labscore = labscore self.totalscore = self.calcscore(200) def __lt__(self, student2): if self.lastname < student2.lastname: return True else: return False def __add__(self,student2): return(self.totalscore + student2.totalscore) def __str__(self): str1 = self.lastname + " " + self.firstname + " " + self.totalscore return(str1)

Now: liststu = [Student("baker","tom",132,88), Student("abbey","steven",122,96), Student("lawrence","sarah",144,85), Student("miller","john",132,92), Student("jones","tina",128,94)] def sortstudentslname(liststu): for i in range(len(liststu)): smallstudent = liststu[i] smallindex = i for j in range(i+1,len(liststu)): if liststu[j] < smallstudent: smallstudent = liststu[j] smallindex = j temp = liststu[i] liststu[i] = liststu[smallindex] liststu[smallindex] = temp return(liststu) def printstu(liststu): for i in range(len(liststu)): print liststu[i] printstu(liststu) sortstudentslname(liststu) printstu(liststu) Even better! liststu.sort() printstu(liststu) class Student(object): def __init__(self, lastname, firstname, testscore, labscore): self.lastname = lastname self.firstname = firstname self.testscore = testscore self.labscore = labscore self.totalscore = self.calcscore(200) def __lt__(self, student2): if self.lastname < student2.lastname: return True else: return False def __str__(self): str1 = self.lastname + " " + self.firstname str += " " + self.totalscore return(str1) def calcscore(self,totalpoints): return((self.testscore + self.labscore)/totalpoints)

list of Operators you can overload: __lt__ ( less than ) __le__ (less or equal to) __eq__ (equal to) __ne__ (not equal to) __gt__ (greater than) __ge__ (greater or equal to) __cmp__ (compare): This one gets called if the previous ones are not defined. __add__ __sub__ __mul__ __div__

Dorm Room Class? For a dorm room class, we’ll need the name of the hall, the number of the room, and the first and second student occupying the room. How? class DormRoom(object): def __init__(self,name, number, studenta,studentb): self.name = name self.number = number self.studenta = studenta self.studentb = studentb

To print the Dorm Room Object: class DormRoom(object): def __init__(self,name, number, studenta,studentb): self.name = name self.number = number self.studenta = studenta self.studentb = studentb def __str__(self): strvar = "Dorm Room " + self.name + str(self.number) + ": {\n" strvar += str(self.studenta) strvar += str(self.studentb) strvar += "}\n\n" return strvar

To create a Dorm Room Object: astudent = Student("baker","tom",132,88) bstudent = Student("miller","john",132,92) aroom = DormRoom("Dickinson",310, astudent,bstudent) print(aroom) # prints the last name of student a in the dorm room print(aroom.studenta.lastname)

Honors Dorm? class DormRoom(object): def __init__(self,name, number, studenta,studentb): self.name = name self.number = number self.studenta = studenta self.studentb = studentb def __str__(self): strvar = "Dorm Room " + self.name + str(self.number) + ": {\n" strvar += str(self.studenta) strvar += str(self.studentb) strvar += "}\n\n" return strvar def upgrade(self,studentc): if self.studenta.testscore < studentc.testscore: if self.studenta.testscore < self.studentb.testscore: self.studenta.lastname = studentc.lastname self.studenta.firstname = studentc.firstname self.studenta.testscore = studentc.testscore self.studenta.labscore = studentc.labscore else: self.studentb.lastname = studentc.lastname self.studentb.firstname = studentc.firstname self.studentb.testscore = studentc.testscore self.studentb.labscore = studentc.labscore elif self.studentb.testscore < studentc.testscore: self.studentb.lastname = studentc.lastname self.studentb.firstname = studentc.firstname self.studentb.testscore = studentc.testscore self.studentb.labscore = studentc.labscore

To Use: liststu = [Student("baker","tom",132,88), Student("abbey","steven",122,96), Student("lawrence","sarah",144,85), Student("miller","john",132,92), Student("jones","tina",128,94)] honorsroom = DormRoom("Dickinson",314,liststu[4],liststu[0]) print honorsroom honorsroom.upgrade(liststu[3]) print honorsroom