List
An ordered, mutable sequence indexed by integer position from 0.
- Lookup by position: O(1).
- Search/delete from middle: O(n).
- Default container when order matters.
When to use: Holding samples, batches, predictions, ordered collections.
Example: preds = [0.1, 0.7, 0.4]; preds.append(0.9); preds.sort() mutates to [0.1, 0.4, 0.7, 0.9].