python · level 2 check

a budget tracker.

Time to build something useful: a budget tracker. Type each spend as a category, a comma and an amount, like `food, 4.50`, then type `done`. The tracker saves every spend to its own CSV file, then reads the file back to build its report.

`read_entry` splits a line and raises a ValueError for anything it cannot use. `Budget.add` refuses amounts that are not more than zero, then adds a row to the CSV. `Budget.totals` reads the rows back and keeps a tally for each category.

The report lists categories A to Z in lined-up columns, adds a total and names your biggest category. Your file starts empty on every run. Fill in each `____`, then run it.

Your program

import csv

class Budget:
    def __init__(self, path):
        self.path = path

def add(self, category, amount):
        if amount <= 0:
            raise ____("the amount must be more than zero")
        with open(self.path, "____", newline="") as file:
            csv.writer(file).____([category, f"{amount:.2f}"])

def totals(self):
        totals = {}
        try:
            with open(self.path, newline="") as file:
                for category, amount in csv.reader(file):
                    totals[category] = totals.get(category, ____) + float(amount)
        except ____:
            print("No spending saved yet.")
        return totals

def read_entry(line):
    parts = line.____(",")
    if len(parts) != 2:
        raise ValueError("type a category, a comma, then an amount")
    category = parts[0].strip().lower()
    if category == "":
        raise ValueError("the category is missing")
    try:
        amount = float(parts[1])
    except ValueError:
        raise ValueError("the amount must be a number")
    return category, amount

def by_total(pair):
    return pair[1]

budget = Budget("budget.csv")
while True:
    line = input("Spend (category, amount) or done: ")
    if line.strip().lower() == "done":
        break
    try:
        category, amount = read_entry(line)
        budget.add(category, amount)
    except ValueError as error:
        print(f"Skipped: {error}.")
    else:
        print(f"Saved {category}: £{amount:.2f}")

print()
totals = budget.totals()
print(f"{'Category':<12}{'Spent':>8}")
for category, total in sorted(totals.____()):
    print(f"{category:<12}{total:>8.____}")
print(f"{'Total':<12}{sum(totals.values()):>8.2f}")
if len(totals) > 0:
    top, top_total = max(totals.items(), key=____)
    print(f"Most spent on {top}: {top_total / sum(totals.values()):.0%} of the total")

Fill in every ____ then run the checks.

1 It saves spends to its CSV and adds them upuses: files and CSV
2 It keeps categories apart and lists them A to Zuses: dictionaries and sorting
3 It skips a line without a commauses: splitting text
4 It refuses amounts that are not numbers or not above zerouses: raising errors
5 It prints a lined-up total and the biggest categoryuses: formatting numbers
6 It copes with no spending at alluses: catching errors

Take as long as you like and try as many times as you want.

a budget tracker.

level up.

playground