Making our own Classes and objects  As in real life, we’re now creating classes of objects.  a class that defines basic characteristics and functions that apply to all objects of that class  Think of a class as a set of functions and variables that belong together to define a particular thing.  E.g., Savings Account classes would have:  A balance #variable, or attribute  An owner’s name #variable, or attribute  The ability to add money to the account #function, or method  The ability to withdraw money from the account #function, or method  An individual’s Savings Account might have:  $ as a balance  Roderick Feckelbocker as the owner’s name

Like creating our own Types  Think of lists:  Lists are a type.  They have methods (functions) associated with them  E.g.,  alist.append(x)  alist.index(x)  alist.pop()  Append(), index(), and pop() are examples of methods (functions) associated with lists.  You can’t use the pop() method (function) with something of type int, right?

If we were to write this: class OurList(object): def __init__(self, alist ): self.thisList = alist # a property! def ourPop(self): # Notice this is still part of the OurList class! x = self.thisList[len(self.thisList) – 1] self.thisList = self.thisList[0:len(self.thisList)-1] return(x)

To create something of the class OurList: class OurList(object): def __init__(self, alist ): self.thisList = alist # a property! def ourPop(self): x = self.thisList[len(self.thisList) – 1] self.thisList = self.thisList[0:len(self.thisList)-1] return(x) ls = OurList([3,2,4,1,5]) # Note that now we have to tell the computer what Class type we’re creating y = ls.ourPop()

Let’s make a class for Rectangles: What methods do we want our rectangle class to have? What properties? Class Rectangle(object): def __init__(self,h,w): self.height = h self.width = w def area(self): return(self.height * self.width)

Let’s make a class for Rectangles: What methods do we want our rectangle class to have? What properties? Class Rectangle(object): def __init__(self,h,w): self.height = h self.width = w def area(self): return(self.height * self.width) rect1 = Rectangle(10, 10) rect2 = Rectangle(20, 5) print(rect1.area())

class Rectangle(object): def __init__(self, width, height): #[CONSTRUCTOR] self.width = width self.height = height def area(self): return self.width * self.height def boxvol(self, x ): return self.width * self.height * x rectangle1 = Rectangle(10, 10) #[EXAMPLES] rectangle2 = Rectangle(20, 5) print(rectangle1.area()) print(rectangle2.boxvol(2)) print(Rectangle(6,8).area())

Classes  Does the problem involve data that is related to a single concept? (e.g., a student, an airline ticket, a car)  Write down the kinds of data in the problem and organize them into classes (some problems may need multiple classes).  Write:  class definition  a list of properties belonging to objects of that class  a constructor (__init__)  An example function  some example class instances.

Employee Class class Employee: def __init__(self, n, s): self.name = n self.salary = s def displayEmployee(self): print("Name : "+self.name+", Salary: "+ self.salary) x = Employee(“bob”,32000) x.displayEmployee()

Employee Class class Employee: def __init__(self, n, s): self.name = n self.salary = s def displayEmployee(self): print("Name : "+self.name+", Salary: "+ self.salary) def getRaise(self,x): self.salary = self.salary + x x = Employee(“bob”,32000) x.displayEmployee() x.getRaise(2000) x.displayEmployee()

Student Class? class Student(object): def __init__(self,firstname,lastname,lab,exam,project): self.firstname = firstname self.lastname = lastname self.lab = lab self.exam = exam self.project = project def getgrade(self): x= self.lab * self.exam * self.project * 0.25 return(x)

Write a class for a circle?  Functions?  Properties?

class Circle(object): """ A circle is a shape with radius, a circumference, and an area radius - number circumference – number (2*pi*radius) area – number (pi*radius**2) """ def __init__(self, x,y,z): self.radius = x self.area=y self.circumference=z x= Circle(3,7,8)

class Circle(object): def __init__(self,x): self.radius = x self.circumference = self.getcirc() self.area = 7 def getcirc(self): return(self.radius * 2 * pi) def area(self): return(self.radius **2 * pi) def changerad(self,x): self.radius = x self.circumference = self.getcirc() circ1 = Circle(3) Print(circ1.area) circ1.changerad(4) Print(circ1.area()) Can we include in the class a function that checks if this circle is bigger than another circle? What type should it return?

from math import * class Circle(object): def __init__(self,x): self.radius = x self.circumference = self.getcirc() self.area = self.getarea() def getcirc(self): return(self.radius * 2 * pi) def getarea(self): return(self.radius **2 * pi) def isbigger(self, circ2): return(self.area > circ2.area) firstcirc = Circle(3) secondcirc = Circle(4) thirdcirc = Circle(2) print(firstcirc.area) print(firstcirc.isbigger(secondcirc)) print(firstcirc.isbigger(thirdcirc))

Student – what if we wanted a grade property? class Student(object): def __init__(self,firstname,lastname,lab,exam,project): self.firstname = firstname self.lastname = lastname self.lab = lab self.exam = exam self.project = project self.grade = self.getgrade() def getgrade(self): x= self.lab * self.exam * self.project * 0.25 return(x) Now make a student. Print his/her grade.

Printing a student object? class Student(object): def __init__(self,firstname,lastname,lab,exam,project): self.firstname = firstname self.lastname = lastname self.lab = lab self.exam = exam self.project = project self.grade = self.getgrade() def getgrade(self): x= self.lab * self.exam * self.project * 0.25 return(x) def __str__(self): return(self.lastname + ","+self.firstname+": \n\tLab: "+\ str(self.lab) + "\n\tExam: " + str(self.exam) +\ "\n\tProject: "+str(self.project)+"\n\tGrade: "+str(self.grade)) x = Student('Bill','Williams',88,76,94) print(x) y = Student('Anne','Stewart',97,67,73) print(y)

What about comparing students? class Student(object): def __init__(self,firstname,lastname,lab,exam,project): self.firstname = firstname self.lastname = lastname self.lab = lab self.exam = exam self.project = project self.grade = self.getgrade() def getgrade(self): x= self.lab * self.exam * self.project * 0.25 return(x) def __str__(self): return(self.lastname + ","+self.firstname+": \n\tLab: "+\ str(self.lab) + "\n\tExam: " + str(self.exam) +\ "\n\tProject: "+str(self.project)+"\n\tGrade: "+str(self.grade)) def __lt__(self,x): if (self.lastname != x.lastname): return self.lastname < x.lastname elif (self.firstname != x.firstname): return(self.firstname < x.firstname) else: return(self.grade < x.grade)

class Student(object): def __init__(self,firstname,lastname,lab,exam,project): self.firstname = firstname self.lastname = lastname self.lab = lab self.exam = exam self.project = project self.grade = self.getgrade() def getgrade(self): x= self.lab * self.exam * self.project * 0.25 return(x) def __str__(self): return(self.lastname + ","+self.firstname+": \n\tLab: "+\ str(self.lab) + "\n\tExam: " + str(self.exam) +\ "\n\tProject: "+str(self.project)+"\n\tGrade: "+str(self.grade)) def __lt__(self,x): if (self.lastname != x.lastname): return self.lastname < x.lastname elif (self.firstname != x.firstname): return(self.firstname < x.firstname) else: return(self.grade < x.grade) x = Student("Robert","Jones",64,71,86) print(x) y = Student("Tom","Miller",72,44,87) print(y) z = Student("Anne","Jones",87,78,92) x = Student("Robert","Jones",64,71,86) print(x) y = Student("Tom","Miller",72,44,87) print(y) z = Student("Anne","Jones",87,78,92) if (x < y): print('hi') else: print('low') if (x < z): print('hi2') else: print('low2')

Others: __eq__(self, other) Defines behavior for the equality operator, ==. __ne__(self, other) Defines behavior for the inequality operator, !=. __lt__(self, other) Defines behavior for the less-than operator, <. __gt__(self, other) Defines behavior for the greater-than operator, >. __le__(self, other) Defines behavior for the less-than-or-equal-to operator, <=. __ge__(self, other) Defines behavior for the greater-than-or-equal-to operator, >=.