Practice / reshaping
Waveform wants the set of listeners who played anything today — each user once, no matter how many tracks they played.
plays
Your task: return the distinct user_id values — one row per unique user, no duplicates.
Assign your answer DataFrame to result. Row order doesn't matter.
playsinput DataFrame| column | type |
|---|---|
| play_id | long |
| user_id | long |
| track_id | long |
| play_id | user_id | track_id |
|---|---|---|
| 1 | 7 | 100 |
| 2 | 7 | 101 |
| 3 | 12 | 100 |
| 4 | 12 | 100 |
| 5 | 30 | 205 |
| 6 | 7 | 205 |
user_id· 3 rowsNarrow to the one column first, THEN dedupe: plays.select("user_id").distinct().
Distinct works on whole rows, so select before you dedupe.
This problem builds on Reshaping Data (~7 min). Pop it open in a new tab if you want a quick recap.