> For the complete documentation index, see [llms.txt](https://docs.seldon.ai/alibi-detect/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.seldon.ai/alibi-detect/api-reference/utils/sampling.md).

# alibi\_detect.utils.sampling

## Functions

### `reservoir_sampling`

```python
reservoir_sampling(X_ref: numpy.ndarray, X: numpy.ndarray, reservoir_size: int, n: int) -> numpy.ndarray
```

Apply reservoir sampling.

| Name             | Type            | Default | Description                                        |
| ---------------- | --------------- | ------- | -------------------------------------------------- |
| `X_ref`          | `numpy.ndarray` |         | Current instances in reservoir.                    |
| `X`              | `numpy.ndarray` |         | Data to update reservoir with.                     |
| `reservoir_size` | `int`           |         | Size of reservoir.                                 |
| `n`              | `int`           |         | Number of total instances that have passed so far. |

**Returns**

* Type: `numpy.ndarray`