1. Lab Demo 1
Dr. Mai Elshehaly

2. What is Python? An interpreted language
Executes instructions directly, without previously compiling a program into machine-language instructions

3. Hello World

4. Indentation acts as {}

5. Classes in Python
A class is a way to group variables and functions that work together to define a certain functionality in your code.
Let’s say we want to write code to simulate a dog
We will create a class named “Dog”
Let’s do this!

6. Create a new file and name it “dog.py”

7. Class definition

8. Class definition

9. Run your code. Nothing happens! Why?
What we wrote so far is a class definition
This is equivalent to saying:
Hypothetically if there is any dog in the street, we assume that it can bark, and it can jump.
This doesn’t mean we’re talking about a specific dog
So we haven’t actually seen a real dog
We only know what dogs in general can do

10. Now let’s instantiate our class
Meaning: we will create an object which is an instance of the class Dog
This will mean a specific dog
Now we can execute some of his actions (functions) and/or read his properties

11. Now run

12. Try this: remove the word self from line 6

13. What happened? We defined the variable canJump twice
The first is a member of the class definition, we can refer to it using the keyword self
The second is local

14. The __init__ function
Notice how we had to call the stopJumpint() method in our code
Nothing happened when we instantiated the class because the class has no entry point
The __init__ function is a special function we define for our class
It gets executed as soon as an object is created

16. What we learned so far: How to define a class
How to create initialization code in __init__ function
How to create an object to instantiate the class
How to call member functions of a class

17. Create a new file: dataMaker.py

18. Import + Class definition

19. Instantiate and run (multiple times)

20. Refresher: Equation of a line passing through 2 points
A + Bx + Cy = 0 Where, A = xB*yA – xA*yB B = yB – yA C = xA – xB

21. Generate points on both sides of the line
Define a vector V of coefficients for the line equation
Calculate new points X by using dot product
For any point on the line: x.V = 0
For any point below the line: x.V is negative
For any point above the line: x.V is positive