# ee.Reducer.toList

Creates a reducer that collects its inputs into a list, optionally grouped into tuples.

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| Usage | Returns |
|---|---|
| `ee.Reducer.toList(*tupleSize*, *numOptional*)` | Reducer |

| Argument | Type | Details |
|---|---|---|
| `tupleSize` | Integer, default: null | The size of each output tuple, or null for no grouping. Also determines the number of inputs (null tupleSize has 1 input). |
| `numOptional` | Integer, default: 0 | The last numOptional inputs will be considered optional; the other inputs must be non-null or the input tuple will be dropped. |