Coding Challenge #3: CSV Data Aggregator

Your sales team just dumped 3 months of transaction data into a CSV file with 10,000+ rows. The VP of Sales wants answers by EOD: "What's our top-selling product category? Which region is underperforming? What's our average deal size?"

Manually scrolling through Excel isn't going to cut it. You need a tool that can crunch the numbers fast and give you actionable insights.

Your Mission

Build a CSV data processor that reads sales data, calculates meaningful aggregations, and generates summary statistics that help drive business decisions.

Requirements

Your tool must:

• Read CSV files with sales transaction data

• Calculate total revenue by product category

• Find top-selling products by quantity and revenue

• Compute average, median, and standard deviation of deal sizes

• Identify best and worst performing sales regions

• Handle missing data gracefully (empty fields, malformed rows)

• Generate both console output and JSON export

• Process files efficiently (handle 10k+ rows without issues)

Sample Input (sales_data.csv)

date,product,category,price,quantity,region,salesperson
2025-01-15,iPhone 15,Electronics,999.00,5,North,Alice Johnson
2025-01-15,MacBook Pro,Electronics,2499.00,2,West,Bob Smith
2025-01-16,Office Chair,Furniture,299.00,10,South,Carol Davis
2025-01-16,Standing Desk,Furniture,599.00,3,East,David Wilson
2025-01-17,iPhone 15,Electronics,999.00,8,North,Alice Johnson
2025-01-17,Coffee Maker,Appliances,149.00,15,West,Eva Brown
2025-01-18,Wireless Mouse,Electronics,79.00,25,South,Frank Miller
2025-01-18,Ergonomic Keyboard,Electronics,159.00,12,East,Grace Lee
2025-01-19,Table Lamp,Furniture,89.00,20,North,Alice Johnson
2025-01-19,,Electronics,199.00,0,West,Bob Smith

Expected Output

Sales Data Analysis Report
==========================
📊 Dataset Overview:
- Total transactions: 10
- Date range: 2025-01-15 to 2025-01-19
- Unique products: 8
- Total revenue: $24,851.00

💰 Revenue by Category:
-----------------------
Electronics: $15,849.00 (63.8%)
Furniture:   $7,567.00 (30.4%)
Appliances:  $2,235.00 (9.0%)

🏆 Top Products by Revenue:
---------------------------
1. MacBook Pro: $4,998.00 (2 units)
2. iPhone 15: $12,987.00 (13 units)
3. Standing Desk: $1,797.00 (3 units)

📈 Deal Size Statistics:
------------------------
Average: $2,485.10
Median: $1,197.00
Std Dev: $1,456.33
Range: $89.00 - $4,998.00

🌎 Regional Performance:
------------------------
North: $14,765.00 (59.4%) - 28 units
West:  $7,483.00 (30.1%) - 17 units
South: $3,771.00 (15.2%) - 35 units
East:  $2,697.00 (10.9%) - 15 units

⚠️  Data Quality Issues:
------------------------
- 1 row with missing product name
- 1 transaction with 0 quantity

💾 Report exported to: sales_analysis_2025-07-19.json

Want the complete solution with optimized algorithms and advanced features? Upgrade to paid subscription for detailed implementations in both Python and Go.

Starter Code Templates

Python Solution