# maximal_marginal_relevance

> **Function** in `langchain_postgres`

📖 [View in docs](https://reference.langchain.com/python/langchain-postgres/_utils/maximal_marginal_relevance)

Calculate maximal marginal relevance.

## Signature

```python
maximal_marginal_relevance(
    query_embedding: np.ndarray,
    embedding_list: list,
    lambda_mult: float = 0.5,
    k: int = 4,
) -> List[int]
```

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[View source on GitHub](https://github.com/langchain-ai/langchain-postgres/blob/9d819182da7e3fb1b815e6c9a6b7c2cd1eb4bc0e/langchain_postgres/_utils.py#L49)