Developing Procedures Student Teaching Lesson

- CB 3.12,3.13 Developing Procedures

What is a procedure?

A procedure is a named group of code that has paramaters and return values. Procedures are known as methods or functions depending on the language.

A procedure executes the statements within it on the parameters to provide a return value.

What are parameters?

Paramaters are input values of a procedure that are specified by arguments.Arguments specify the values of the parameters when a procedure is called.

By creating theses algorithms the readibility of code increases and the complexity decreases. This is becasue a function’s name can tell the reader what action it will perform, and by calling it, the code becomes more clean and easy to understand.

What is a return value?

A return value is the value that is returned when a function or a method is called.

That return value can be assigned or printed

Procedures are used to create algorthims that can perform certain actions or return values. When a procedure returns a value, theis information must be stored in a variable for later use. However some procedures like the MOVE_FORWARD() perform an action, and don’t return a value. The image above provides an example of where procedures that don’t output a value would be used.

'''

A 60$ item recieves a 20% discount and taxed at 8%.
PROCEDURE applyDiscount(cost, percentDiscounted)
{
    temp ← 100 - percentDiscounted
    temp← temp/ 100
    cost ← cost *temp
    RETURN(cost)
}

price ← applyDiscount(60, 20)
This is how we get the final price with the discount by calling the procedure and assigning it to the price variable.


PROCEDURE applyTax(cost, percentTaxed)
{
    temp ← 100 + percentTaxed
    temp← temp/ 100
    cost ← cost *temp
    RETURN(cost)
}
price ← applyTax(price, 8)
This applys the 8% tax to the price determined after the discount.
'''

Popcorn Hack 1

Given the applyTax procedure above: How would you call the procedure to get it to find the price using cost = 50, and percentTaxed = 10, and what value will it return?

#code here
'''

price = applyTax(50,10)

'''

#This would set the variable price to the value 55.

What Are Functions?

• Collections of code
• Divides large program into smaller chunks
• Better readability
• Less repetitive code
• More efficient code
• Good organization

What Are The Components of a Function?

• The function declaration
• The parameters (input). This is also referred to as an argument when a value is being passed to the actual function.
• The functionality
• The return value (output)
• Calling the function

# Defining Functions
#
# def function_name(parameter1, parameter2, etc..):
#     code here...
#
#     return return_value;

# return the value of parameter1 plus parameter2;
def add(parameter1, parameter2): # creates a function that takes in two parameters
    solution = parameter1 + parameter2; # sets solution to the sum of parameter1 and parameter2
    return solution; # return solution
    
print(add(5, 5)); # prints the return value of add(5,5)

Popcorn Hack 2:

1. Make a function that returns the difference of two numbers

# Code here

def subtract(n1, n2):
    return n1-n2

subtract(7.2,1)

6.2

What is a Class?

• A class is an outline for a set of nested functions and variables.
• There are instance variables
• Functions
• Constructor method (Required)
• To String method
• Getter method
• Setter method

How Does a Class Work?

# Defining Classes
class person:
    def __init__(self, name, age, ): # constructor
        self.name = name
        self.age = age
    
    def getName(self): # method to create get name
        return self.name
    
    def getAge(self): # method to create get age
        return self.age
    
    def setName(self, name): # method to create set name
        self.name = name
        
    def setAge(self, age): # method to create set age
        self.age = age
        
    def yearOlder(self): # method to increment age by 1
        self.age += 1
        
    def __str__(self): # method that returns a string when the object is printed
        return (f"My name is {self.name} and I am {self.age} years old.")

Person1 = person("John Doe", 15)
print(Person1)


print(Person1)

My name is John Doe and I am 15 years old.
My name is John Doe and I am 15 years old.

Popcorn Hack 3:

1. Create a Car class which has the attributes model, vehicle name, and price

2. Create instances of the following cars

• Name: Honda Civic , Model Year: 2018 , Price: $13,000
• Name: Toyota Prius, Model Year: 2023 , Price: $28,000
• Name: Chevrolet Impala, Model Year: 2020 , Price: $22,000

class car:
    def __init__(self, model, year, price):
        self.model = model
        self.year = year
        self.price = price
    def getModel(self):
        return self.model
    def getYear(self):
        return self.year
    def getPrice(self):
        return self.price
    def __str__(self):
        return (f"{self.model} , Model Year: {self.year}, Price: ${self.price}")
        
car1 = car("Honda Civic", 2018, 13000)
print(car1)

car2 = car("Toyota Prius", 2023, 28000)
print(car2)

car3 = car("Chevrolet Impala", 2020, 22000)
print(car3)

Honda Civic , Model Year: 2018, Price: $13000
Toyota Prius , Model Year: 2023, Price: $28000
Chevrolet Impala , Model Year: 2020, Price: $22000

Homework:

Assignment 1: How do you use functions?

Create a turtle python function that...

1. Takes a single parameter as the number of sides
2. Outputs a shape corresponding to the number of sides
3. Call the function with the argument being a variable with the user input

Hint:

#New Assignment 1

arr1 = [2,1,3,2,0,2,0,0,4,2,0,0,0,2,0,0,1,2,3,0,7,4,5,2,1,2,3,4,6]

def return_unique(arr):
    uq = []
    for element in arr:
        if element not in uq:
            uq.append(element)
            
    return uq

print(return_unique(arr1))

[2, 1, 3, 0, 4, 7, 5, 6]

#Old Assignment 1 (Bonus)
import turtle

pen = turtle.Turtle(); # pen is the instance of Turtle which has methods that do certain actions

# Necessary methods:
# .forward(50) - moves the pen forward 50 units
# .right(angle) - turns the pen angle degrees right   
# OR
# .left(angle) - turns the pen angle degrees left

def shape(sides):
    for i in range(sides):
        pen.forward(150/sides)
        pen.right(180-(sides-2)*180/sides)

numsides = input('How many sides do yoUUUU wnat in YOUUUURRRR shape?!?!!?!: ')
shape(int(numsides))

#Tested, works in replit

---------------------------------------------------------------------------

ModuleNotFoundError                       Traceback (most recent call last)

/Users/remyliu/vscode/csablog/_notebooks/2023-10-03-developingProceduresP5.ipynb Cell 20 line 1
----> <a href='vscode-notebook-cell:/Users/remyliu/vscode/csablog/_notebooks/2023-10-03-developingProceduresP5.ipynb#X23sZmlsZQ%3D%3D?line=0'>1</a> import turtle
      <a href='vscode-notebook-cell:/Users/remyliu/vscode/csablog/_notebooks/2023-10-03-developingProceduresP5.ipynb#X23sZmlsZQ%3D%3D?line=2'>3</a> pen = turtle.Turtle(); # pen is the instance of Turtle which has methods that do certain actions
      <a href='vscode-notebook-cell:/Users/remyliu/vscode/csablog/_notebooks/2023-10-03-developingProceduresP5.ipynb#X23sZmlsZQ%3D%3D?line=4'>5</a> # Necessary methods:
      <a href='vscode-notebook-cell:/Users/remyliu/vscode/csablog/_notebooks/2023-10-03-developingProceduresP5.ipynb#X23sZmlsZQ%3D%3D?line=5'>6</a> # .forward(50) - moves the pen forward 50 units
      <a href='vscode-notebook-cell:/Users/remyliu/vscode/csablog/_notebooks/2023-10-03-developingProceduresP5.ipynb#X23sZmlsZQ%3D%3D?line=6'>7</a> # .right(angle) - turns the pen angle degrees right   
      <a href='vscode-notebook-cell:/Users/remyliu/vscode/csablog/_notebooks/2023-10-03-developingProceduresP5.ipynb#X23sZmlsZQ%3D%3D?line=7'>8</a> # OR
      <a href='vscode-notebook-cell:/Users/remyliu/vscode/csablog/_notebooks/2023-10-03-developingProceduresP5.ipynb#X23sZmlsZQ%3D%3D?line=8'>9</a> # .left(angle) - turns the pen angle degrees left


ModuleNotFoundError: No module named 'turtle'

Assignment 2:

Create a student class that...

1. Has a constructor that takes three parameters as attributes
2. • email
   • name
   • grade
3. Three getter methods to access the name, email, and grade
4. Three setter methods to modify the name, email, and grade
5. A to string method that returns the three instance variables in this format - "My name is {name}. My email is {email}. My grade is {grade}
6. Create an instance of the class that corresponds with you

class student:
    def __init__(self, email, name, grade):
        self.email = email
        self.name = name
        self.grade = grade
    def getName(self):
        return self.name
    def getEmail(self):
        return self.email
    def getGrade(self):
        return self.grade
    def __str__(self):
        return (f"My name is {self.name}. My email is {self.email}. My grade is {self.grade}")
    
student1 = student('myre.wx@gmail.com', 'Remy', 12)
print(student1)

My name is Remy. My email is myre.wx@gmail.com. My grade is 12