# LabeledPairwiseStringEvalChain

> **Class** in `langchain_classic`

📖 [View in docs](https://reference.langchain.com/python/langchain-classic/evaluation/comparison/eval_chain/LabeledPairwiseStringEvalChain)

Labeled Pairwise String Evaluation Chain.

A chain for comparing two outputs, such as the outputs
of two models, prompts, or outputs of a single model on similar inputs,
with labeled preferences.

## Signature

```python
LabeledPairwiseStringEvalChain()
```

## Extends

- `PairwiseStringEvalChain`

## Properties

- `requires_reference`

## Methods

- [`from_llm()`](https://reference.langchain.com/python/langchain-classic/evaluation/comparison/eval_chain/LabeledPairwiseStringEvalChain/from_llm)

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[View source on GitHub](https://github.com/langchain-ai/langchain/blob/c59e83a1ffba63d709ea4847445845edd82085dc/libs/langchain/langchain_classic/evaluation/comparison/eval_chain.py#L411)