""" 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 """ import csv import os 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 — fully implemented # ----------------------------------------------------------------------> def add_expense(category, amount, note=""): """ Append one expense record to the CSV file with robust input validation. """ # 1. Validation: Check that the category is valid if category not in CATEGORIES: print(f"Invalid category. Choose from: {CATEGORIES}") return # 2. Validation: Check that the amount is positive if amount <= 0: print("Amount must be a positive number.") return # 3. Save to file date = datetime.now().strftime("%Y-%m-%d") 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. """ expenses = [] if not os.path.exists(DATA_FILE): return expenses try: with open(DATA_FILE, "r", newline="", encoding="utf-8") as f: reader = csv.DictReader(f) for row in reader: try: # Convert row metrics accurately row["amount"] = float(row["amount"]) expenses.append(row) except (ValueError, KeyError): continue # Skip malformed lines safely except Exception as e: print(f"Error reading file: {e}") return expenses def list_expenses(): """ Print every expense record in a clear, formatted readable table layout. """ expenses = read_all_expenses() # --- Write your display code here --- import csv def list_all_expenses(): try: with open("expenses.csv", "r") as file: reader = csv.DictReader(file) print("\n=== All Expenses ===") has_data = False # Print header row print(f"{'Date':<12} | {'Category':<12} | {'Amount':<10} | {'Note'}") print("-" * 55) for row in reader: # Normalize category for consistency category = row['category'].strip().capitalize() print(f"{row['date']:<12} | {category:<12} | {row['amount']:<10} | {row['note']}") has_data = True if not has_data: print("No expenses recorded yet.") except FileNotFoundError: print("No expense file found. Please add an expense first.") def monthly_summary(): """ Print the total amount spent per category for the current calendar month. """ now = datetime.now() current_month = now.strftime("%Y-%m") month_label = now.strftime("%B %Y") expenses = read_all_expenses() # Filter for items that belong to the current year-month pattern filtered_expenses = [row for row in expenses if row["date"].startswith(current_month)] print(f"\nSummary for {month_label}") print("-" * 35) for row in filtered_expenses: if cat in totals: totals[cat] += row["amount"] totals["Other"] += row["amount"] for category, amount in totals.items(): if amount > 0: # Only display active categories with entries print(f"{category:<20} ${amount:>10.2f}") print(f"{'Total':<20} ${grand_total:>10.2f}") def filter_by_category(category): """ Return only the expenses that match the given category name (case-insensitive). expenses = read_all_expenses() return [row for row in expenses if row["category"].lower() == category.lower()] def export_to_csv(output_filename, category=None): Write a filtered/unfiltered report data structure to a brand new CSV file. """ if category: data_to_export = filter_by_category(category) data_to_export = read_all_expenses() if not data_to_export: print("No data available to export.") return try: with open(output_filename, "w", newline="", encoding="utf-8") as f: writer = csv.DictWriter(f, fieldnames=CSV_HEADERS) writer.writeheader() writer.writerows(data_to_export) print(f"Successfully exported {len(data_to_export)} records to '{output_filename}'.") except Exception as e: print(f"Failed to export file: {e}") # ---------------------------------------------------------------------> # Menu and entry point — complete execution flow # ---------------------------------------------------------------------> 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(" 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}':") print(f" {'Date':<12} {'Amount':<10} {'Note'}") print(" " + "-" * 40) for row in results: print(f" {row['date']:<12} ${row['amount']:<9.2f} {row['note']}") elif choice == "5": filename = input("Output filename (e.g. report.csv): ").strip() if not filename: print("Filename cannot be blank.") continue 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()