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Create a Program to Implement User Interaction in Python Assignment Solution.


Write a program to implement user interaction in python.

Requirements and Specifications

program to implement user interaction in python

Source Code


# How this program can be improved?

# Using a list is too difficult to manage because we have to like store

# different kinds of data on each index. There must be a better way to

# organize the data like using a dictionary or a class.


# Constant variables for accessing a product information from a list




# Constant variables for accessing customer information from a list



# Constant variables for accessing a purchase of a customer on its list of

# purchased products



def init_default_products():


Create the default products upon run of program

:return: List of products


# This is going to be a list of list. Each item in the list is a product

# represented as a list which holds the name, stock, and price

products = [

["Cup", 5, 4.99],

["Plate", 5, 10.00],

["Bowl", 5, 7.50],

["Spoon", 5, 1.99],

["Fork", 5, 1.00],

["Air", 5, 0],

["Python", 1, -1]


return products

def find_product(products, name):


Find the product given a name

:param products: List of products to be searched

param name: Target name

:return: Found product


for product in products:

if product[PRODUCT_NAME] == name:

return product

return None

def find_customer(customers, name):


Find the customer given a name

:param customers: List of customers to be searched

:param name: Target name

:return: Found customer


for customer in customers:

if customer[CUSTOMER_NAME] == name:

return customer

return None

def add_new_purchase(products, customers):


Module that allows to enter a new single purchase for a customer.

:param products: Reference for purchasing a product

:param customers: Where to add a new customer if new, otherwise reference for discount.

:return: None


# Ask for the customer's name, abort if no customer name is applied

customer_name = input("Enter customer name: ").strip()

if customer_name == "":

print("A customer name is required.")


# Ask for the product, abort if not given

product_name = input("Enter product name: ").strip()

if product_name == "":

print("A product name is required.")


# Check that the product exists, abort if not found

product = find_product(products, product_name)

if product is None:

print("The product does not exist.")


# Abort if product has no price

if product[PRODUCT_PRICE] < 0:

print("The product cannot be sold because there is no price.")


# Ask for the quantity, abort if it is 0 or negative

quantity = int(input("Enter quantity: "))

if quantity <= 0:

print("A positive quantity is required.")


# Check that there is enough stock for the quantity required, abort if not

if quantity > product[PRODUCT_STOCK]:

print("The product does not have enough stock for the given quantity.")


# Calculate the total cost, add 10% discount if it was a previous customer

total_cost = product[PRODUCT_PRICE] * quantity

customer = find_customer(customers, customer_name)

if customer is None:

# A new customer cannot order a free product

if product[PRODUCT_PRICE] == 0:

print("New customers cannot order free products.")


# For new customer we will create a new record for it

# Index 0 is the name while Index 1 is the list of products they purchased

customer = [customer_name, []]



# Apply 10% discount

total_cost -= (total_cost * 0.10)

product[PRODUCT_STOCK] -= quantity

print(customer_name + " purchased " + str(quantity) + " x " + str(product_name))

print("Unit price: $" + "{:.2f}".format(product[PRODUCT_PRICE]))

print("Total price: $" + "{:.2f}".format(total_cost))

# Update customer product purchase history

customer[CUSTOMER_PURCHASES].append([product, quantity])

def update_products(products):


Allow the user to set new products for sale

:param products: List of products to be reset

:return: None


# Get the product names, abort if none provided

names = input("Enter product names separate it by space: ").strip()

if names == "":

print("Product names are required.")


# Get the prices, abort if none provided

prices = input("Enter the prices separate it by space: ").strip()

if prices == "":

print("The prices are required.")


# Get the stocks, abort if none provided

stocks = input("Enter the stock quantities separate it by space: ").strip()

if stocks == "":

print("The stock quantities are required.")


# Break the names, prices, and stocks into lists. Make sure that

# They are of the same lengths

names = names.split()

prices = prices.split()

stocks = stocks.split()

if len(names) != len(prices) or len(names) != len(stocks):

print("Invalid input. Either a name, price and/or quantity did not align with the input.")

print("If a product has no price, then enter a non positive value.")


# Re-create the products


for i in range(len(names)):

products.append([names[i], int(stocks[i]), float(prices[i])])

def calculate_customer_total_purchase_cost(customer):


Total the purchase cost of a customer based on products it purchased

:param customer: Customer to be processed

:return: Total purchase cost


total_cost = 0

for purchase in customer[CUSTOMER_PURCHASES]:


return total_cost

def find_most_valuable_customer(customers):


Display the most valuable customer which is the customer with the most

highest amount of total purchase.

:param customers: List of customers for search

:return: None


most_valuable_customer = None

# Search each customer and compare it with one other to find the most

# with purchase cost

for customer in customers:

if most_valuable_customer is None or calculate_customer_total_purchase_cost(customer) \

> calculate_customer_total_purchase_cost(most_valuable_customer):

most_valuable_customer = customer

if most_valuable_customer is None:

print("No valuable customer found.")


print("The most valuable customer is '" + most_valuable_customer[CUSTOMER_NAME] + "'")

def replenish_products(products):


Reset the stock quantities for all products

:param products: Products to be processed

:return: None


# Ask for the starting quantity, abort if invalid

stocks = int(input("Enter the starting quantities of products: "))

if stocks < 0:

print("Invalid quantity, it should be a zero or positive value.")


for product in products:

product[PRODUCT_STOCK] = stocks

def display_customers(customers):


Display all customers

:param customers: List of customers for display

:return: None


print("Existing Customers:")

for customer in customers:

print(" " + customer[CUSTOMER_NAME])

def display_products(products):


Display all products

:param products: List of products for display

:return: None


print("Name".ljust(20) + "Price".rjust(10) + "Stock".rjust(10))

# Display each product's info

for product in products:

print(product[PRODUCT_NAME].ljust(20), end="")

if product[PRODUCT_PRICE] > 0:

print("${:.2f}".format(product[PRODUCT_PRICE]).rjust(10), end="")

elif product[PRODUCT_PRICE] == 0:

print("FREE".rjust(10), end="")


print("UNKNOWN".rjust(10), end="")


def count_purchased_product(customer, product_name):


Count how many times a customer purchased a product


count = 0

for purchase in customer[CUSTOMER_PURCHASES]:

if purchase[PURCHASED_PRODUCT][PRODUCT_NAME] == product_name:

count += purchase[PURCHASED_QUANTITY]

return count

def display_customer_and_products_table(products, customers):


Display a table of products and the customers as a 2 dimensional table

showing the quantities purchased for each customer on a product

:param products: List of products

:param customers: List of customers

:return: None


# Print out a header

print("".ljust(20), end="")

for product in products:

print(product[PRODUCT_NAME].ljust(15), end="")


# Print out the customers and purchases for each product

for customer in customers:

print(customer[CUSTOMER_NAME].ljust(20), end="")

# For each customer count the total quantity of products

for product in products:

count = count_purchased_product(customer, product[PRODUCT_NAME])

print(str(count).ljust(15), end="")


def main():


This will be our entry point of the program to handle the main control

flow of logic.

:return: None


# Start with default products

products = init_default_products()

# Start with an empty customers

customers = []

while True:

# Display a menu that allows the user to perform command

print("What would you like to do?")

print("1. Add a new purchase")

print("2. Set a new list of products for purchase")

print("3. Replenish products")

print("4. Display customers")

print("5. Display products")

print("6. Find most valuable customer")

print("7. Display customer and product table")

print("0. Exit")

option = int(input("Option: "))

if option == 1:

add_new_purchase(products, customers)

elif option == 2:


elif option == 3:


elif option == 4:


elif option == 5:


elif option == 6:


elif option == 7:

display_customer_and_products_table(products, customers)

elif option == 0:



# Start the program