Popcorn Hack (Classwork) 🍿 If you have a Python list of numbers, but want to keep certain numbers (EX: even ones), you can actually use what is called a "list comprehension." What this essentially does is it creates another list, but you can apply a filter or operation to it to help you get specific outputs. 
numbers = [1, 2, 3, 4, 5, 6]
even_numbers = [num for num in numbers if num % 2 == 0]

print(even_numbers)  # Output: [2, 4, 6], thanks to the list comprehension! 

# List comprehensions allow you to write shorter code that is easier to read. It could even save you time! 


[2, 4, 6]
Hacks (Homework)
  • Create a program that lets users manage a list of their choosing. Users can add elements, remove them, check if an element exists, and display the current list.
  • A function that can find the maximum and minimum value of a list using iteration.
Below is a sample code with explanations if you are stuck. Use this as a guide. Do NOT copy and paste. 
# Basic Python Program for List Management and Finding Max/Min Values

# Function to display the list
def display_list(aList):
    print("Current list:", aList)

# Function to add an item to the list
def add_item(aList, item):
    aList.append(item)
    print(f"'{item}' added to the list.")

# Function to remove an item from the list
def remove_item(aList, item):
    if item in aList:
        aList.remove(item)
        print(f"'{item}' removed from the list.")
    else:
        print(f"'{item}' not found in the list.")

# Function to check if an item exists in the list
def check_item(aList, item):
    if item in aList:
        print(f"'{item}' is in the list.")
    else:
        print(f"'{item}' is not in the list.")

# Function to find the maximum value in the list
def find_max(aList):
    max_val = aList[0]
    for num in aList:
        if num > max_val:
            max_val = num
    return max_val

# Function to find the minimum value in the list
def find_min(aList):
    min_val = aList[0]
    for num in aList:
        if num < min_val:
            min_val = num
    return min_val

# Initialize the list
user_list = []

# Simulating inputs instead of using input() for Jupyter
actions = [
    ('add', 'apple'),
    ('add', 'banana'),
    ('check', 'banana'),
    ('remove', 'apple'),
    ('display', None),
    ('add', 10),
    ('add', 5),
    ('max', None),
    ('min', None),
    ('quit', None)
]

# Simulating a loop to execute the operations
for action, value in actions:
    if action == 'add':
        add_item(user_list, value)
    elif action == 'remove':
        remove_item(user_list, value)
    elif action == 'check':
        check_item(user_list, value)
    elif action == 'display':
        display_list(user_list)
    elif action == 'max':
        if user_list and all(isinstance(x, (int, float)) for x in user_list):
            print("Max value in the list:", find_max(user_list))
        else:
            print("The list is empty or contains non-numeric values.")
    elif action == 'min':
        if user_list and all(isinstance(x, (int, float)) for x in user_list):
            print("Min value in the list:", find_min(user_list))
        else:
            print("The list is empty or contains non-numeric values.")
    elif action == 'quit':
        print("Exiting program.")
        break


'apple' added to the list.
'banana' added to the list.
'banana' is in the list.
'apple' removed from the list.
Current list: ['banana']
'10' added to the list.
'5' added to the list.
The list is empty or contains non-numeric values.
The list is empty or contains non-numeric values.
Exiting program.
How it Works:
  1. Predefined Actions:
    • Since Jupyter Notebooks are not well-suited for interactive input() calls, a list of actions called actions is predefined, simulating user inputs.
    • Each action is a tuple of the form (operation, value). For example, ('add', 'apple') adds the item 'apple' to the list.
  2. Operations Loop:
    • A loop processes each action. Based on the operation (add, remove, check, etc.), the corresponding function is called.
    • When the operation is 'quit', the loop exits.
  3. Max/Min Operations:
    • The find_max() and find_min() functions are only called when the list contains numerical values. You can mix both string and numerical values in the list, but find_max() and find_min() only make sense for numbers.
Customization:
  • You can modify the actions list to simulate different scenarios, and the program will print the output in sequence as it processes the actions.