Python Project: CSV Report

What you are building

You parse a small CSV of product, quantity, and unit price. The program multiplies quantity by price for each row, sums revenue per product, and prints a report sorted by revenue, highest first.

Stay in the Python editor at /try. This track is not HTML, C, or C++. The CSV lives in a multiline string. You do not read a file from disk, and you do not install packages. The standardcsv module is enough.

Skills used

• csv.DictReader on a string via io.StringIO
• int and float conversions on cells
• A dict of running revenue per product
• sorted with a key and reverse=True
• A printed table of product, units, and revenue

Parse a CSV string

In this editor there is no sales.csv on disk. Put the same text in a string. Wrap it withStringIO so csv can read it like a file. DictReader uses the header row as keys.

import csv
from io import StringIO

raw = """product,qty,price
Mug,3,4.50
Notebook,2,8.00
Pen,10,1.25
"""

reader = csv.DictReader(StringIO(raw))
for row in reader:
    print(row["product"], row["qty"], row["price"])

Cells arrive as strings. "3" is not 3 until you call int. "4.50"needs float. Convert once when you walk the rows.

Revenue per product

Line revenue is quantity times unit price. Two Mug rows must add, not overwrite. Store a pair per product: units sold and money earned. A dict keyed by product name holds that pair.

import csv
from io import StringIO

raw = """product,qty,price
Mug,3,4.50
Notebook,2,8.00
Mug,1,4.50
"""

totals = {}
reader = csv.DictReader(StringIO(raw))
for row in reader:
    name = row["product"]
    qty = int(row["qty"])
    price = float(row["price"])
    units, revenue = totals.get(name, (0, 0.0))
    totals[name] = (units + qty, revenue + qty * price)

print(totals)

Complete program

Five sales rows, three products. The report sorts by revenue. Mug earns 18.00, Notebook 24.00, Pen 12.50. Notebook should print first. Run the whole script at /try.

import csv
from io import StringIO

RAW = """product,qty,price
Mug,3,4.50
Notebook,2,8.00
Mug,1,4.50
Pen,10,1.25
Notebook,1,8.00
"""

totals = {}
reader = csv.DictReader(StringIO(RAW))
row_count = 0
for row in reader:
    name = row["product"].strip()
    qty = int(row["qty"])
    price = float(row["price"])
    units, revenue = totals.get(name, (0, 0.0))
    totals[name] = (units + qty, revenue + qty * price)
    row_count += 1

ranked = sorted(totals.items(), key=lambda item: item[1][1], reverse=True)
grand_units = sum(units for units, _ in totals.values())
grand_rev = sum(revenue for _, revenue in totals.values())

print("CSV sales report")
print("Rows parsed:", row_count)
print()
print(f"{'product':<12} {'units':>6} {'revenue':>10}")
print("-" * 30)
for name, (units, revenue) in ranked:
    print(f"{name:<12} {units:>6} {revenue:>10.2f}")
print("-" * 30)
print(f"{'TOTAL':<12} {grand_units:>6} {grand_rev:>10.2f}")

Common mistakes

• Opening a real path such as open("sales.csv") in this editor. There is no project folder file. Use the multiline string.
• Sorting by product name when you wanted money. The key is item[1][1]: the revenue inside the tuple.
• Multiplying strings: "10" * 3 repeats text. Convert types first.
• Forgetting the header. If you use csv.reader and do not skip row 1, int("qty")crashes.
• Installing a spreadsheet library. This report is stdlib only: csv, io, dicts.

How to extend / Practice tasks

Leave the five demo rows in place until 54.50 matches.

1. Add a line Mug,2,4.50 and confirm Mug units become 6 and revenue 27.00, with a new grand total of 63.50.
2. Sort by units instead of revenue and print which product moves to the top (Pen).
3. Skip any row whose quantity is 0 or whose price is negative. Test by insertingSticker,0,1.00 and Lamp,-1,20.00 and checking that TOTAL units stay 17.