Practice / joins
The Daily Grind's marketing team wants to win back customers who signed up but never actually ordered anything.
You have two DataFrames:
customers
orders
Your task: return the customer_id and name of every customer who has no matching row in orders.
Assign your answer DataFrame to result. Row order doesn't matter.
customersinput DataFrame| column | type |
|---|---|
| customer_id | long |
| name | string |
| customer_id | name |
|---|---|
| 100 | Priya |
| 101 | Sam |
| 102 | Wei |
| 103 | Nadia |
ordersinput DataFrame| column | type |
|---|---|
| order_id | long |
| customer_id | long |
| order_id | customer_id |
|---|---|
| 1 | 100 |
| 2 | 100 |
| 3 | 101 |
customer_idname· 2 rowsA left_anti join keeps left rows with no match on the right — exactly the
customers who never ordered: customers.join(orders, on="customer_id", how="left_anti").
This problem builds on Joins (~8 min). Pop it open in a new tab if you want a quick recap.