Variables

A variable is an abstraction inside a program that can hold a value
It organizes data by labeling it with a descriptive name
It consists of three parts: name, value, and type
Using meaningful variables names helps with readability of program code and understanding of what values are represented by the variables

Naming Variables

Do's	Don'ts	Why
highScore	highestScoreInTheGame	Keep it simple and easy to read, having variables that are too complicated can cause your code to become messy later on
highScore	highscore	Differentiate the words in your variable with a capital letter. Makes things easier to read
firstName	n	not specific enough/vague
isRaining	is it raining	spaces are improper syntax
phoneNumber	555-number	dashes are improper syntax and numbers should be avoided in variable names

Types of data
- Integer: A number
- Text/string: A word
- Boolean: Data that determines if something is true or false

name = "table1" #string
print(name, type(name))

number = 4 #integer
print(number, type(number))

isAbsent = False
print(isAbsent, type(isAbsent))

table1 <class 'str'>
4 <class 'int'>
False <class 'bool'>

A list of data can also be stored in variables. Why is that useful?

print/retrieve specific values in the list without creating a lot of variables
easily remove/add/change items into the list

colors = ["red", "orange", "yellow"]
print(colors[2])

yellow

Assignments

The assignment operator allows a program to change the value represented by a variable
Used to assigning values to variables

Operator	Description	Syntax	Outcome when print(a)
=	Assign value of right side of expression to left side operand	a = b	b
+=	Add right side operand with left side operand and then assign to left operand	a += b	a + b
-=	Subtract right operand from left operand and then assign to left operand: True if both operands are equal	a -= b	a - b
*=	Multiply right operand with left operand and then assign to left operand	a *= b	a * b
/=	Divide left operand with right operand and then assign to left operand	a /= b	a / b
**=	Calculate exponent(raise power) value using operands and assign value to left operand	a **= b	a ^ b

a = 1
b = 2
a = b
print(a)

The value stored in a variable will be the most recent value assigned

a = 1
b = a
a = 2
print(b)

1

Changing Values

currentScore = 10
highScore = currentScore
currentScore = 7
print(highScore)

your turn! Here are 3 problems for you to solve

num1 = 5
num2 = 9
num1 = num2

print(num1)
print(num2)

num1 = 15
num2 = 25
num3 = 42
num2 = num3
num3 = num1
num1 = num2

print(num1)
print(num2)
print(num3)

Which of these will show the sum?

num2 += num1
print(num1)
print(num2)

print(str(num1)+ str(num2))
print(num1 + num2)

Data Abstraction

Method used in coding to represent data in a useful form, by taking away aspects of data that aren't being used in the situation
Variables and lists are primary tools in data abstraction
Provides a separation between the abstract properties of a data type and the concrete details of its representation

Lists & Strings

List = ordered sequence of elements
Element = individual value in a list that is assigned to a unique index
Index = a way to reference the elements in a list or string using natural numbers; each element of a string is referenced by an index
String = ordered sequence of characters (Letters, numbers, special characters)
Note: index starts at 1 for AP Exam, must be whole numbers, cannot be negative, and goes up to the number of elements in the list
We can represent a list or string using a variable

Example of a List - Colors

Index	Element
1	Green
2	Blue
3	Purple
4	Pink

At Index 1, the element is green, at index 2, the element is blue, etc.

Managing the Complexity of a Program through Data Abstraction

Data abstractions help manage complexity in programs by giving a collection of data a name without referencing the specific details of the representation
Developing a data abstraction to use in a program can result in a program that is easier to develop and maintain

Using Lists as Data Abstractions

What are Lists?

Allow for data abstraction
Bundle variables together
Store multiple elements
Allows multiple related items to be treated as a single value
Give one name to a set of memory cells
Can keep adding elements to it as needed
Can store elements as a single variable by using a list

3 Types of List Operations

Assigning values to a list at certain indices
Creating an empty list and assigning it to a variable
Assigning a copy of one list to another list (setting one list equal to another list)

1. Assigning values to a list at certain indices

colorsList=["pink", "yellow", "green", "blue", "orange"]

print(colorsList)

['pink', 'yellow', 'green', 'blue', 'orange']

2. Creating an empty list and assigning it to a variable

colorsList=[] # can be used if you want to create a list that can be filled with values later

3. Assigning a copy of one list to another list (setting one list equal to another list)

# copy of the list is made; the list isn't sorted in place
def Reverse(lst): # defining variable: lst 
    new_lst = lst[::-1] 
    return new_lst
 
lst = ["pink", "green", "purple", "yellow", "orange", "blue", "black"]
print(Reverse(lst)) # reverse 1st

['black', 'blue', 'orange', 'yellow', 'purple', 'green', 'pink']

What is Managing Complexity?

Improving code readability
Reducing the need for new variables as more data is collected
Can easily update data
Can easily convert data to different forms

How do Lists Help Manage the Complexity of a Program?

Don’t need as many variables
Can easily change the number of variables
Can apply the same mathematical computation (through an algorithm) to all the elements in the list

Data Abstraction Practice

Manage the complexity of the given code below using a list. Re-write the code segment in a less complex way, but with the same result.

color1="green"
color2="red"
color3="pink"
color4="purple"
color5="blue"
color6="brown"

print(color1)
print(color2)
print(color3)
print(color4)
print(color5)
print(color6)

green
red
pink
purple
blue
brown

Answer

colorList=["green", "red", "pink", "purple", "blue", "brown"]

print(str(colorList))

['green', 'red', 'pink', 'purple', 'blue', 'brown']

AP Exam Use of Data Abstraction

With the properties of the AP Exam pseudocode, lists work differently from what we've learned in python so far, here are the two major differences:

The index does not start at 0 but 1
There is only one method of interchanging data between lists, and that is completely overwriting previous list data with the other list\n",

Homework

You will turn in a program that utilizes lists and variables as it's primary function, options could be a quiz, a sorter, database, or wherever your imagination brings you. You will be graded on how well you understood the concepts and if you used anything other than just the simplest parts

Quiz template, if you do use it, fix the issues, and add more to it than it's current barebones state. I would recommend using it to create something related to school.

quesCount = 0

# Use a dictionary for the questions
quesList = ["Question1", "Question2", "Question3", "Question4"]

# Use a dictionary for the correct solutions
soluList = ["Solution1", "Solution2", "Solution3", "Solution4"]

quesAmount= len(quesList)

hrm quesCount <= quesAmount:
    print(quesList[quescount] + "\n")
    guess = input()
    if(guess == soluList[quesamOOuaunt]):
        print("Correct!")
    else: 
        print("Incorrect! The correct answer was " + soluList(quescount) + "\n")
    quesCount += 1




print("Final score: " + str(score))

Name	Complete	Correct	Complexity	Final Score	Notes
Sreeja Gangapuram	1/1	1/1	0.8/1	0.95/1	Utilized a list as well as other functions to make code more efficient Very clear output of what happened;Printed correct answers, score, and questions
Moein Taleban	1/1	1/1	0.7/1	0.9/1	Utilized a list but could've enforced some functions to maximize efficiency Output is not as clear as it could be Only the questions are printed and the number 4 is not referred to as the score which might be confusing
Ekam Kaire	1/1	1/1	1/1	1/1	Unique and creative use of lists and dictionaries Stores and outputs data based on user's preference Utilizes functions and if statements
Azeem Khan	1/1	1/1	0.8/1	0.95/1	Used for loop to iterate through the questions. Efficient and allows for clean code Output is clear and specific, states question and answer Score is given as a number and a percentage
Jishnu Singiresu	1/1	1/1	0.8/1	0.95/1	created a function which is called at the end nice and clean output
Soham Kamat	1/1	1/1	1/1	1/1	creative and advanced use of lists
Trey	1/1	1/1	0.6/1	0.8/1	Used list to print information no use of functions or loops
Joshua Williams	1/1	1/1	0.8/1	0.95/1	Used for loop to iterate through the questions. Efficient and allows for clean code Output is clear and specific, states question and answer
Yuri Subramaniam	1/1	1/1	1/1	1/1	creative and advanced use of lists
Max Wu	1/1	1/1	0.8/1	0.95/1	Utilized a list as well as other functions to make code more efficient Very clear output of what happened;Printed correct answers, score, and questions
Kalani Omana	1/1
Jonathan	1/1	1/1	/1	/1
Alan Liu Sui	1/1	1/1	/1	/1
Dhruva Iyer	1/1	1/1	/1	/1
Ethan	1/1	1/1	/1	/1
Dash Penning	1/1	1/1	/1	/1
Jeffery Fonesca	1/1	1/1	/1	/1
Ahah Biabani	1/1	1/1	/1	/1
Abdullah	1/1	1/1	/1	/1
Luke Angelini	.9/1	0.7/1	0.7/1	0.7/1