The Scenario
A retail chain stores its data across three separate systems: `customers.csv` (customer demographics), `orders.csv` (order headers), and `order_items.csv` (line items with product and price). Your analyst needs a single, denormalized DataFrame to work from.
The Brief
Write the pandas code to load, merge, reshape, and aggregate these three files into one clean DataFrame. Handle schema mismatches (different column names, date formats, missing keys).
Deliverables
- The complete Python script showing the merge strategy (inner, left, etc.) and join keys
- How you handled schema mismatches (column renames, type casting, date parsing)
- The final aggregated output: revenue per customer, with at least 2 derived columns
Submission Guidance
Show that you understand the difference between inner, left, and outer joins. A wrong join type silently drops data.
Submit Your Work
Your submission is graded against the rubric on the right. If you pass, you get a public Badge URL you can share on LinkedIn. There is no draft save, so work offline first and paste your finished response here.