Practice / aggregations
Waveform's merch store wants to see what each shopper is holding.
You have the cart DataFrame:
Your task: return each user_id and a column items — the distinct products in that user's cart, as an alphabetically sorted list.
Assign your answer DataFrame to result. Row order doesn't matter.
cartinput DataFrame| column | type |
|---|---|
| user_id | long |
| item | string |
| user_id | item |
|---|---|
| 1 | Vinyl |
| 1 | Tote |
| 1 | Vinyl |
| 1 | Sticker |
| 1 | Hoodie |
| 1 | Cap |
| 1 | Poster |
| 2 | Mug |
| 2 | Pin |
| 2 | Tee |
user_iditems· 2 rowsF.collect_set("item") gathers the distinct items per group. Wrap it in
F.sort_array(...) so the list comes back in a stable alphabetical order.
This problem builds on One Row Per Group (~5 min). Pop it open in a new tab if you want a quick recap.