Question

IN PYTHON

You are building a program for a Point of Sale (POS) machine for a fruit store. The inventory and price list are stored in a file (i.e. items.txt) with an example as follows:

     banana 3 1.25
     apple 6 1.75
     orange 32 0.5
     pear 55 2.5

For illustration, the first line implies that "There are 3 bananas in the inventory and the price of a banana is $1.25"

You have to write four functions:

1. The first function readstockprice takes as argument the filename (i.e. items.txt) as input and creates the following dictionaries:

a. A stock dictionary for which the key is the fruit name and the value is the numbers (int) of that fruit in the inventory

b. A price dictionary for which the key is the fruit name and the value is the price (float) of that fruits.

Now let us see what happens when a sale is made. A customer's order consists of a list of fruits and the numbers (int) they wish to purchase. This is in the form of a dictionary similar in structure to the stock dictionary.

2. The function readshoppinglist takes as argument the filename (i.e. shoppinglist.txt) and read the content of the file into shopping dictionary. For example, shoppinglist.txt contains following:

     banana 2
     apple 12
     orange 6

3. The function process_order takes as argument the customer's shopping list dictionary shopping and stock & price dictionaries. This function does three tasks:

a. Print number of items sold for each item where stock quantity is more than or equal to sell quantity.

b. Update the store inventory for each item sold to the customer and only include in the total price actual items sold to the customer if the item is available in the store. That is, if the item’s value in stock is 0, the customer is no longer sold that item and is not charged for it.

c. Print the total cost of the sale.

Example output:

     You bought 2 banana
     You bought 6 orange
     Cost of items sold is: 5.5

4. Function updatestockprice takes as argument the filename (i.e. items.txt), stock & price dictionaries as inputs and writes them back to file (i.e. items.txt) in the similar format. For example after the function is called item.txt should have:

     banana 1 1.25
     apple 6 1.75
     orange 26 0.5
     pear 55 2.5

Answer 1

All the explanation is in the code comments. Hope this helps!

Please take care of indentation in python by referring to code screenshots.

Code:

import os

# function takes as argument the filename (i.e. items.txt) as input
# and creates the following dictionaries -
# A stock dictionary, key -> fruit name and value -> numbers (int) of that fruit
# A price dictionary, key -> fruit name and value -> price (float) of that fruit
def readstockprice(filename):

   # open file
   file = open(filename)
   stock = {}
   price = {}

   # read line by line from file
   for line in file:

       # split the line to get item name, stock and price
       val = line.split()
       item = val[0]
       # convert to required datatype
       numbers = int(val[1])
       cost = float(val[2])

       # add it to the dictionary
       stock[item] = numbers
       price[item] = cost

   # close the file
   file.close()

   # return stock and price dictionary
   return stock, price

# function takes as argument the filename (i.e. shoppinglist.txt)
# and read the content of the file into shopping dictionary
def readshoppinglist(filename):

   # open file
   file = open(filename)
   shopping = {}

   # read line-by-line from shopping list
   for line in file:

       # get the item name and its quantity
       val = line.split()
       item = val[0]
       numbers = int(val[1])

       # add to the shoppinglist dictionary
       shopping[item] = numbers

   # close file
   file.close()

   # return the shopping dictionary
   return shopping

# function takes as argument the customer's shopping list dictionary shopping and stock & price dictionaries.
# This function does three tasks -
# 1. Print number of items sold for each item where stock quantity is more than or equal to sell quantity.
# 2. Update the store inventory for each item sold to the customer
# and only include in the total price actual items sold to the customer if the item is available in the store.
# That is, if the item’s value in stock is 0, the customer is no longer sold that item and is not charged for it.
# 3. Print the total cost of the sale.
def process_order(shopping, stock, price):

   total_cost = 0

   for item in shopping:
      
       # 1 -> print number of items sold
       if(stock[item] >= shopping[item]):

           item_qty_sold = shopping[item]
           print('You bought', item_qty_sold, item)

           # 2 -> update the stock inventory
           stock[item] = stock[item] - item_qty_sold

           # add to the total price
           total_cost = total_cost + (item_qty_sold * price[item])

   # 3-> print total cost
   print('Cost of items sold is:', total_cost)

# Function takes as argument the filename (i.e. items.txt), stock & price dictionaries as inputs
# and writes them back to file (i.e. items.txt) in the similar format.
def updatestockprice(filename, stock, price):

   # write to temporary file
   temp_file = open('temp.txt', 'w')

   # loop through each item and write in the same format
   for item in stock:
       temp_file.write(item + ' ' + str(stock[item]) + ' ' + str(price[item]) + '\n')

   # close the file
   temp_file.close()

   # remove the old items.txt file
   os.remove(filename)
   # rename the temporary file to items.txt
   os.rename('temp.txt', filename)

# function calls
stock, price = readstockprice('items.txt')
shopping = readshoppinglist('shoppinglist.txt')
process_order(shopping, stock, price)
updatestockprice('items.txt', stock, price)

Sample output:

Code screenshots: