Due: Friday, February 28 at 11:59 pm
Submission: On Courseworks
Please read the instructions carefully. An incorrectly formatted submission may not be counted.
There is one question in this assignment.
This assignment starts from skeleton code called finances.py.
Please include comments in your code detailing your thought process where appropriate.
Put finances.py in a folder called uni-hw4 (so for me this would be tkp2108-hw4).
Then compress this folder into a .zip file.
For most operating systems, you should be able to right click and have a “compress” option in the context menu.
This should create a file called tkp2108-hw4.zip (with your uni).
Submit this on courseworks.
In this homework, we will build a real application using lists, dictionaries, and files.
The skeleton code below provides a simple version of the application. This application does the following:
There is a lot of code to unpack, with comments inline to provide context. We will walkthrough this code in class, but you do not need to modify any of the existing functions.
Your task is to do the following.
Add at least 2 of the commands from the following list. Do not choose the same calculation twice (e.g. sum credits and sum debits).
Add at least 1 of the commands from the following list:
Add at least 1 of the commands from the following list:
Add at least 1 other functionality, use your imagination! If you can’t think of anything, you can do one from Listing or Cleaning above.
import os
from csv import DictReader, DictWriter
# This is some example data, so you can see the format
# and the data structures (list of dicts)
EXAMPLE_FINANCES = [
{"date": "2025-02-17", "amount": "500", "category": "Work Study"},
{"date": "2025-02-17", "amount": "-200", "category": "Senior Gala"},
{"date": "2025-02-18", "amount": "-15.5", "category": "JJ's"},
{"date": "2025-02-18", "amount": "50", "category": "Dining Dollars"},
{"date": "2025-02-19", "amount": "-5", "category": "Joe Coffee"},
{"date": "2025-02-20", "amount": "-50.0", "category": "Music Hum Performance"},
{"date": "2025-02-21", "amount": "-5", "category": "Joe Coffee"},
]
#####################
# UTILITY FUNCTIONS #
#####################
def write_finances_csv(file_path, data):
"""This is a helper function to write the list
of dictionaries in the format above to a file"""
file = open(file_path, 'w')
csvwriter = DictWriter(file, fieldnames=["date", "amount", "category"])
for row in data:
csvwriter.writerow(row)
file.close()
def read_finances_csv(file_path):
"""This is a helper function to read data in the format
above from a file"""
if not os.path.exists(file_path):
return EXAMPLE_FINANCES
file = open(file_path, 'r')
data = []
for row in DictReader(file, fieldnames=["date", "amount", "category"]):
data.append(row)
file.close()
return data
#####################
# COMMAND FUNCTIONS #
#####################
def print_all_entries(data):
"""This function takes a list of dictionaries and prints out
all of the entries with some nice spacing and formatting"""
print("\nAll entries:")
for i, entry in enumerate(data):
date = entry["date"]
amount = entry["amount"]
category = entry["category"]
print(f"\t{i}: {date}: ${amount}\t{category}")
# return data without changes
return data
def reset_to_examples(data):
"""This function ignores `data` and instead
returns the example data from above"""
return EXAMPLE_FINANCES
def clear_entries(data):
"""This data removes all entries from data. We can 'cheat'
and just ignore `data` and return an empty list instead"""
return []
def add_entry(data):
"""This function will prompt the user for date, amount, and category,
and append the new dictionary entry to the end of the list"""
date = input("Enter the date: ")
amount = input("Enter the amount: ")
category = input("Enter the category: ")
data.append({"date": date, "amount": amount, "category": category})
return data
def delete_entry(data: list):
"""This function will show the entries to the user and then
prompt them for the index of the entry they want to delete"""
"""delete an entry"""
# First print all the entries to remind the user
print_all_entries(data)
# Now ask for an entry
index = int(input("Enter the index of the entry to delete, or -1 to cancel: "))
if index >= 0:
# remove it from the list
data.pop(index)
return data
#################
# MAIN FUNCTION #
#################
def main():
"""This is our main function. It is the primary entry point into our program
and it does a couple of things. See the inline comments for details"""
# Our list of commands.
# This is a dictionary mapping a command (in our case an integer)
# to the description of the command and the function. All of our
# commands take the the form:
#
# new_data = function(current_data)
#
# So they will take the current list of expenses and return a (maybe different)
# list of expenses.
#
# You will add new commands here as you implement them
commands = {
"0": ["Save and quit", None],
"1": ["Print all entries", print_all_entries],
"2": ["Reset to examples", reset_to_examples],
"3": ["Clear all entries", clear_entries],
"4": ["Add new entry", add_entry],
"5": ["Delete an entry", delete_entry],
# YOUR NEW COMMANDS HERE
}
# This is the file we will work from
finances_csv_filename = "finances.csv"
# Load up the data
data = read_finances_csv(finances_csv_filename)
# Print a welcome message
print("Welcome to the finances app!")
# Enter an infinite loop until the user
# chooses to quit
while True:
# Print the available commands
print("\nPick a command to continue:")
for command_number in commands:
description, function = commands[command_number]
print(f"\t{command_number}. {description}")
# Get the user's choice
choice = input("Enter a command number: ")
# If the choice is not valid, print an error message
if choice not in commands:
print("Invalid choice. Please try again.")
continue
# Handle saving and quitting
if choice == "0":
break
# Otherwise, call the function associated with the choice
# Pass in the data and return the new/modified data
data = commands[choice][1](data)
# Finally, save the changes
write_finances_csv(finances_csv_filename, data)
if __name__ == "__main__":
main()