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Building a Pizza Party Bill Splitter with Easy Money and Easy CSV

Combine Easy Money and Easy CSV to calculate discounts, tax, and split costs among friends, then save an itemized summary to a spreadsheet.

What we are building

When ordering food for a group, calculating each person's share after coupons and tax usually requires multiple calculations. This example calculates the total, divides it evenly among four friends, and writes a clean summary to a CSV file that can be read back and shared.

from py_simple import (
    add_tax,
    calculate_discount,
    format_money,
    read_csv_to_list,
    split_bill,
    write_csv_from_list,
)

items = [
    {"item": "Pizza Party Pack", "price": 60.0},
    {"item": "Garlic Bread", "price": 12.0},
    {"item": "Soda Pitcher", "price": 8.0},
]

subtotal = sum(item["price"] for item in items)
discounted = calculate_discount(subtotal, 10.0)
with_tax = add_tax(discounted, 8.0)
per_person = split_bill(with_tax, 4)

summary_rows = [
    {"description": "Subtotal", "amount": format_money(subtotal)},
    {"description": "After 10% coupon", "amount": format_money(discounted)},
    {"description": "Total with 8% tax", "amount": format_money(with_tax)},
    {"description": "Per person (4 friends)", "amount": format_money(per_person)},
]

write_csv_from_list("pizza_party.csv", summary_rows)
saved = read_csv_to_list("pizza_party.csv")
for row in saved:
    print(f"{row['description']}: {row['amount']}")

Example output:

Subtotal: $80.00
After 10% coupon: $72.00
Total with 8% tax: $77.76
Per person (4 friends): $19.44

What happened?

  1. calculate_discount(subtotal, 10.0) applies a 10% discount to the initial sum and returns the discounted total.
  2. add_tax(discounted, 8.0) computes the total after applying an 8% sales tax rate.
  3. split_bill(with_tax, 4) divides the bill evenly among 4 people.
  4. format_money() converts numbers and decimals into formatted currency strings with two decimal places.
  5. write_csv_from_list() saves the rows to pizza_party.csv, using dictionary keys as header columns.
  6. read_csv_to_list() reads the saved spreadsheet back into a list of row dictionaries so values can be displayed.

Why use these helpers?

Calculating currency with floating-point math often introduces rounding errors. easy_money handles exact decimal values under the hood and formats them cleanly. Paired with easy_csv, you can save and load tabular records without writing boilerplate file-opening and CSV writer code.