Args:
            embedding: Embedding to look up documents similar to.
            k: Number of Documents to return. Defaults to 4.
            fetch_k: Number of Documents to fetch to pass to MMR algorithm.
            lambda_mult: Number between 0 and 1 that determines the degree
                        of diversity among the results with 0 corresponding
                        to maximum diversity and 1 to minimum diversity.
                        Defaults to 0.5.
        Returns:
            List of Documents selected by maximal marginal relevance.
        """
        if namespace is None:
            namespace = self._namespace
        results = self._index.query(
            [embedding],
            top_k=fetch_k,
            include_values=True,
            include_metadata=True,
            namespace=namespace,
            filter=filter,
        )
        mmr_selected = maximal_marginal_relevance(
            np.array([embedding], dtype=np.float32),
            [item["values"] for item in results["matches"]],
            k=k,
            lambda_mult=lambda_mult,
        )
        selected = [results["matches"][i]["metadata"] for i in mmr_selected]
        return [
            Document(page_content=metadata.pop((self._text_key)), metadata=metadata)
            for metadata in selected
        ]
[docs]    def max_marginal_relevance_search(
        self,
        query: str,
        k: int = 4,
        fetch_k: int = 20,
        lambda_mult: float = 0.5,
        filter: Optional[dict] = None,
        namespace: Optional[str] = None,
        **kwargs: Any,
    ) -> List[Document]:
        """Return docs selected using the maximal marginal relevance.