# SingleKeyEvalConfig

> **Class** in `langchain_classic`

📖 [View in docs](https://reference.langchain.com/python/langchain-classic/smith/evaluation/config/SingleKeyEvalConfig)

Configuration for a run evaluator that only requires a single key.

## Signature

```python
SingleKeyEvalConfig()
```

## Extends

- `EvalConfig`

## Properties

- `reference_key`
- `prediction_key`
- `input_key`

## Methods

- [`get_kwargs()`](https://reference.langchain.com/python/langchain-classic/smith/evaluation/config/SingleKeyEvalConfig/get_kwargs)

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[View source on GitHub](https://github.com/langchain-ai/langchain/blob/6fb37dba71da807af60aa7b909f71f0625a666bf/libs/langchain/langchain_classic/smith/evaluation/config.py#L57)