""" expense_tracker.py ================== Project: Personal Expense Tracker Difficulty: Beginner Skills: Python, CSV module, datetime module Time: Low (a few hours) What you will build: A command-line tool that lets you log daily expenses, view them in a formatted table, see a monthly breakdown by category, and export a filtered report to a new CSV file. How to run: python expense_tracker.py Learning goals: - Reading and writing CSV files - Working with Python's datetime module - Organising code into small, focused functions - Building a simple interactive text menu Roadmap: Step 1: Project is already set up — run it and explore the menu Step 2: Complete add_expense() with category and amount validation Step 3: Complete list_expenses() to print a formatted table Step 4: Complete monthly_summary() to group totals by category Step 5: Complete filter_by_category() to search by category name Step 6: Complete export_to_csv() to save a filtered report Step 7: Test with at least 10 sample entries across different months """ import csv import os import shutil from datetime import datetime # --------------------------------------------------------------------------- # Configuration # --------------------------------------------------------------------------- # The file where all expense records are stored DATA_FILE = "expenses.csv" # Valid category names — entries outside this list are rejected CATEGORIES = ["Food", "Transport", "Bills", "Entertainment", "Health", "Other"] # Column headers written to the CSV on first run CSV_HEADERS = ["date", "category", "amount", "note"] # --------------------------------------------------------------------------- # File initialisation # --------------------------------------------------------------------------- def initialize_file(): """ Create the CSV file with headers if it does not already exist. Called once at startup to ensure the file is ready for appending. """ if not os.path.exists(DATA_FILE): with open(DATA_FILE, "w", newline="", encoding="utf-8") as f: writer = csv.writer(f) writer.writerow(CSV_HEADERS) print(f"Created new expense file: {DATA_FILE}") # --------------------------------------------------------------------------- # Core functions — complete the TODOs to make each one work # --------------------------------------------------------------------------- def add_expense(category, amount, note=""): """ Append one expense record to the CSV file. Args: category (str): Must be one of the strings in CATEGORIES. amount (float): The expense amount. Must be greater than zero. note (str): Optional description (e.g. "lunch at work"). TODO: 1. Check that category is in CATEGORIES. If not, print an error message and return without writing. Example: print(f"Invalid category. Choose from: {CATEGORIES}") 2. Check that amount is greater than zero. If not, print an error message and return without writing. Example: print("Amount must be a positive number.") 3. The date and file-write logic below is already complete. Once your validation passes, the row is saved automatically. """ # --- Write your validation code above this line --- # Get today's date in YYYY-MM-DD format date = datetime.now().strftime("%Y-%m-%d") # Append the new row to the CSV file with open(DATA_FILE, "a", newline="", encoding="utf-8") as f: writer = csv.writer(f) writer.writerow([date, category, round(float(amount), 2), note]) print(f"Expense of {amount:.2f} added under '{category}'.") def read_all_expenses(): """ Read every row from the CSV file and return them as a list of dicts. Returns: list[dict]: Each dict has keys: date, category, amount, note. Amount is converted to float. Returns an empty list if the file has no data rows. This function is used by list_expenses(), monthly_summary(), and filter_by_category() — complete it once and it powers all three. TODO: 1. Open DATA_FILE for reading with csv.DictReader. 2. Loop through each row and convert row["amount"] to float. 3. Append each row dict to a results list. 4. Return the list. Example output: [ {"date": "2024-03-01", "category": "Food", "amount": 12.50, "note": "lunch"}, ... ] """ expenses = [] # --- Write your file-reading code here --- return expenses def list_expenses(): """ Print every expense record in a readable table format. Expected output: Date Category Amount Note ---------- ------------ ------- -------------------- 2024-03-01 Food 12.50 lunch 2024-03-02 Transport 3.20 bus ticket ... Total: 15.70 across 2 entries. TODO: 1. Call read_all_expenses() to get the data. 2. If the list is empty, print "No expenses recorded yet." and return. 3. Print the header row and a separator line. Tip: use Python's f-string padding: f"{'Date':<12}" left-aligns 'Date' in a field 12 characters wide. 4. Loop through expenses and print each row with consistent padding. 5. After the table, print the total count and total amount. """ expenses = read_all_expenses() # --- Write your display code here --- pass def monthly_summary(): """ Print the total amount spent per category for the current calendar month. Expected output: Summary for March 2024 ---------------------- Food 45.20 Transport 18.00 Bills 120.00 ---------------------- Total 183.20 TODO: 1. Get the current month and year with datetime.now(). 2. Call read_all_expenses() and filter rows where the date starts with the current year-month string (e.g. "2024-03"). Tip: row["date"].startswith("2024-03") 3. Build a dictionary mapping category -> total amount. Example: totals = {"Food": 0.0, "Transport": 0.0, ...} 4. Loop through the filtered expenses and add each amount to the right category key. 5. Print the month heading, each category with its total, and the grand total at the bottom. """ now = datetime.now() current_month = now.strftime("%Y-%m") month_label = now.strftime("%B %Y") # --- Write your summary code here --- pass def filter_by_category(category): """ Return only the expenses that match the given category. Args: category (str): The category to search for (case-insensitive). Returns: list[dict]: Matching expense rows. TODO: 1. Call read_all_expenses() to get all rows. 2. Filter rows where row["category"].lower() == category.lower(). 3. Return the filtered list. """ # --- Write your filter code here --- return [] def export_to_csv(output_filename, category=None): """ Write a report to a new CSV file. Args: output_filename (str): The name of the file to create. Example: "march_food_report.csv" category (str|None): If provided, export only rows in that category. If None, export everything. TODO: 1. If category is given, call filter_by_category(category) to get rows. Otherwise, call read_all_expenses() for all rows. 2. If there are no rows, print a message and return. 3. Open output_filename for writing with csv.DictWriter. 4. Write the header row using writeheader(). 5. Write all data rows using writerows(). 6. Print a confirmation message with the number of rows exported. """ # --- Write your export code here --- pass # --------------------------------------------------------------------------- # Menu and entry point — already complete, no changes needed here # --------------------------------------------------------------------------- def show_menu(): """Print the main menu and return the user's choice as a string.""" print("\n" + "=" * 35) print(" Personal Expense Tracker") print("=" * 35) print(" 1. Add an expense") print(" 2. List all expenses") print(" 3. Monthly summary") print(" 4. Filter by category") print(" 5. Export to CSV") print(" 6. Quit") print("=" * 35) return input(" Choose (1-6): ").strip() def prompt_category(): """Show the category list and return the user's selection.""" print("\nCategories:") for i, cat in enumerate(CATEGORIES, start=1): print(f" {i}. {cat}") return input("Enter category name: ").strip() def main(): """Run the expense tracker — the main application loop.""" initialize_file() while True: choice = show_menu() if choice == "1": cat = prompt_category() try: amt = float(input("Amount (e.g. 12.50): ").strip()) except ValueError: print("Please enter a valid number for the amount.") continue note = input("Note (optional, press Enter to skip): ").strip() add_expense(cat, amt, note) elif choice == "2": list_expenses() elif choice == "3": monthly_summary() elif choice == "4": cat = prompt_category() results = filter_by_category(cat) if not results: print(f"No expenses found for category '{cat}'.") else: print(f"\nFound {len(results)} expense(s) in '{cat}':") for row in results: print( f" {row['date']} {row['amount']:>8.2f} {row['note']}" ) elif choice == "5": filename = input( "Output filename (e.g. report.csv): " ).strip() cat = input( "Filter by category? (press Enter to export all): " ).strip() or None export_to_csv(filename, category=cat) elif choice == "6": print("\nGoodbye. Keep tracking those expenses!\n") break else: print("Invalid choice. Enter a number between 1 and 6.") if __name__ == "__main__": main()