COSC 101 Homework 7: Fall 2024

Due date: Thursday, November 14, 11:59pm

Introduction

According to data from Feeding America, 11% of people in Madison county (which is where Hamilton is located) faced food insecurity in 2022. The Hamilton Food Cupboard is a critical community resource for individuals facing food insecurity. They operate on a client choice food pantry model, in which individuals can choose what products they receive, just like shopping at a grocery store.

To make the Hamilton Food Cupboard even more convenient and welcoming to community members needing food assistance, the Food Cupboard has (fictitiously) decided to offer food pick-up/delivery service similar to companies like Mercato. Your task is to write a program that clients can use to select which foods they would like to receive from the Food Cupboard.

Please write your code in the template file hw7_mercato.py included with this homework. The file includes an almost empty main function that contains some variables that have been pre-populated for your program to use initially.

Task 1: Two Standalone Functions

Your first task is to incrementally write and test two fruitful functions. As you did in the lastest lab, we want you to practice test-driven development by using doctests that guide each function’s implementation. Hence, you must write each appropriate doctest before adding the code that covers this particularity. Refer to your last lab implementation as a reference to include the relevant import and the call to execute the doctests in hw7_mercato.py where you will complete these two stand-alone functions.

Subtask A: getUnique

First, create and implement a function called getUnique that takes a list of strings and returns a new list that contains only the unique items from the argument list in the order they originally appear. The argument list should not be modified. For example:

• getUnique(["A", "B", "CD", "A", "A", "CD", "efg"]) should return a new list containing ['A', 'B', 'CD', 'efg']

Subtask B: filter

Similarly, add a function called filter that takes two list of strings, listA and listB, as well as a target string, target. This function returns a new list containing elements out of listB where the corresponding index of listA is equal to target. The argument lists should not be modified. For example:

• filter(["FY", "Soph", "FY", "Junior", "Senior", "FY"], ["COS101", "COSC202", "COS102", "COSC315", "COSC435", "FSEM135"], "FY") should return a new list containing ["COS101", "COS102", "FSEM135"].
  This is because, "FY" (i.e. target) appears at indices 0, 2, and 3 of listA, so the returned list contains the corresponding values at these indices in listB)

• filter(["FY", "Soph", "FY", "Junior", "Senior", "FY"], ["COS101", "COSC202", "COS102", "COSC315", "COSC435", "FSEM135"], "Grad") should return an empty list []

Once you have implemented, debugged, and fully tested through doctests on these two generic functions you are ready to tackle the design and implementation for the next problem.

Do not forget these two functions, they must be used to solve your Mercato program.

Task 2: Food Mercato Program

Next, you need to implement the Food Mercato program according to the specifications below. The trace1.pdf, trace2.pdf and trace3.pdf files provided with this homework demonstate what a correctly working program should look like. Study these examples closely to determine the patterns that help you design and structure your program.

Welcome banner

The execution of your program should begin by displaying a welcome banner:

  _____                 ,_ _                           
 () |_  _   _   _|     /| | |   _  ,_   _   _, _|_  _  
   /| |/ \_/ \_/ |      | | |  |/ /  | /   / |  |  / \_
  (/   \_/ \_/ \/|_/    | | |_/|_/   |/\__/\/|_/|_/\_/ 

Working in the main function in hw7_mercato.py, you should utilize our provided function to display this welcome banner.

Select a category

Next, the program should display the unique categories of food from which a client can select. The categories should be displayed in the order they first occur in the categories list included in the provided main and should be numbered starting at 1. After listing the categories, the program should ask the user: Which category do you want?

Categories:
1. Fruit
2. Vegetable
3. Grain
4. Dairy
Which category do you want?

If the client enters a non-numeric value or a number that is not one of the displayed options, then the program should print the message Enter a number between 1 and _ (replacing _ with the largest possible number) and ask the user again: Which category do you want?. The process should repeat until the user enters a valid choice. For example:

Which category do you want? F
Enter a number between 1 and 4
Which category do you want? Fruit
Enter a number between 1 and 4
Which category do you want? 10
Enter a number between 1 and 4
Which category do you want? 1

Remember the string function "13".isdigit() – it will be useful to solve part of this input validation!

Select a food item

Next, the program should display the available foods in the selected category. The foods list included in the hw7_mercato.py includes foods across all categories. A food’s category is determined by filtering the food list using the categories list. For example, foods[1] is 'Broccoli' and categories[1] is 'Vegetable'. Similar to above, the foods should be displayed in the order they occur in the foods list and should be numbered starting at 1. After listing the foods, the program should ask the client: Which food do you want?

For example, if the user chose the ‘Fruit’ category, the program would output the following:

Foods:
1. Bananas
2. Pears
Which food do you want? 

As before, if the client enters a non-numeric value or a number that is not one of the displayed options, then the program should print the message Enter a number between 1 and _ (replacing _ with the largest possible number) and again ask the user Which food do you want?

Desired units

Next, the program should display the client’s remaining credits for selecting food. In the client choice food pantry model, clients are normally given a credit budget based on a number of factors (e.g., household size), and each item is assigned a “cost” in credits. For simplicity, your program will assume a client starts with 10 credits and each unit of a food costs one credit regardless of the category or specific food.

The program should ask the client: How many units of 'xxxx' do you want?, xxx is replaced by the name of food item previously selected. If the client enters a non-numeric value or a number greater than their remaining credits, then the program should print the message Enter a number between 1 and _ (replacing _ with the number of remaining credits) and again ask the user How many units do you want?

For example:

Remaining credits: 10
How many units of 'Pears' do you want? 12
Enter a number between 1 and 10
How many units of 'Pears' do you want? five
Enter a number between 1 and 10
How many units of 'Pears' do you want? 5

The number of units should be deducted from the client’s remaining credits. If the client still has remaining credits, then the client should again be asked to select a category, select a food, and enter the desired number of units.

Display summary

After the client has used all of their credits, the program should display the foods they requested and the number of each item using the following format:

Foods requested:
+ Milk (x6)
+ Cauliflower (x4)

The items must be displayed in the order they were selected by the client.

Note that a client may request some units of an item, then request more units of that same item, but the item should only appear once in the order summary with the total amount requested.

For example:

Categories:
1. Fruit
2. Vegetable
3. Grain
4. Dairy
Which category do you want? 3

Foods:
1. Wheat bread
2. Walnuts
Which food do you want? 2

Remaining credits: 10
How many units of 'Walnuts' do you want? 6

Categories:
1. Fruit
2. Vegetable
3. Grain
4. Dairy
Which category do you want? 3

Foods:
1. Wheat bread
2. Walnuts
Which food do you want? 2

Remaining credits: 4
How many units of 'Walnuts' do you want? 4

Foods requested:
+ Walnuts (x10)

Program structure

For this homework, you must decide how to structure your program (you may want to use a flow chart to guide your implementation).

It is fundamental that your program

• contains multiple functions, and
• does not contain repeated code.

If you find yourself copying and pasting (nearly) the same code, you should create a function that can be called from multiple points in your program!

For all functions you write, you should ensure:

• it does one thing (i.e., one specific task);
• it takes parameters and returns a value (or values), but does not modify the variables provided in the starter code;
• it is fairly short.

Write a little bit of code at a time (one function at most – but maybe just a few lines in a function) and test as you go. Writing most or all of the code you think you need then testing afterward is a terrible strategy that will lead to frustration. Do a little bit at a time!

Remember to document each of your functions with annotations, docstrings, and doctests.

Task 3: Reading from File

Once you have implemented all of the above functionality, you must make your program work with categories and foods lists that are different than those originally provided in hw7_mercato.py. These alternate lists will be read in from an external file, where each line of the file will contain a single food item and its respective category – example below:

Frozen Quiche 
Produce Oranges 
Canned Chickpeas
Frozen Gelato 
Canned Beans
Canned Olives
Produce Mangoes
Produce Grapes

After displaying the welcome banner, your program should now ask the user if they wish to use the foods and categories contained in an external food_data.txt file. If the user responds with Y/y, the foods and categories are determined by the contents of food_data.txt, otherwise the default lists are used.

Your program does not need to account for a missing or improperly formatted food_data.txt file. Below is an example:

  _____                 ,_ _                           
 () |_  _   _   _|     /| | |   _  ,_   _   _, _|_  _  
   /| |/ \_/ \_/ |      | | |  |/ /  | /   / |  |  / \_
  (/   \_/ \_/ \/|_/    | | |_/|_/   |/\__/\/|_/|_/\_/ 

Do you wish to read in food data from food_data.txt?  
Enter (Y) to read from a file, or any other input to use default values: Y

Categories:
1. Frozen
2. Produce
3. Canned
Which category do you want? 1

Foods:
1. Quiche
2. Gelato
Which food do you want? 1
...

Grading

When we are assessing your code, higher levels of achievement are demonstrated, in part, by

• All lines of output are present
• Lines of output have proper formatting, including spacing and blank lines
• Use spaces and blank lines in code for readability
• Variables are appropriately named and used
• Functions are appropriately named and definitions include type annotations, and meaningful docstrings
• Functions are used to capture patterns and minimize repeated code
• Functions are used to break down problems and employ abstraction each is relatively short, doing only one thing and takes few arguments
• Loops are appropriately used to abstract repeated patterns
• Code is clean (for example, remove code you commented out)
• Code is elegant (for example, limit excessive code, ask yourself, can I do this a simpler way)
• Code is structured so that the logic is clear and easy to follow.
• Any information needed inside a function should be passed as parameters; anything done by a function that needs to be used by the caller of the function should be returned from the function.

Submission Instructions

Submit your Python file, hw7_mercato.py, to the platform indicated in your class section.

Remember to complete the questions at the top of the hw7_mercato.py file before submitting.