np.array([embedding], dtype=np.float32),
            embeddings,
            k=k,
            lambda_mult=lambda_mult,
        )
        selected_indices = [indices[0][i] for i in mmr_selected]
        selected_scores = [scores[0][i] for i in mmr_selected]
        docs_and_scores = []
        for i, score in zip(selected_indices, selected_scores):
            if i == -1:
                # This happens when not enough docs are returned.
                continue
            _id = self.index_to_docstore_id[i]
            doc = self.docstore.search(_id)
            if not isinstance(doc, Document):
                raise ValueError(f"Could not find document for id {_id}, got {doc}")
            docs_and_scores.append((doc, score))
        return docs_and_scores
[docs]    def max_marginal_relevance_search_by_vector(
        self,
        embedding: List[float],
        k: int = 4,
        fetch_k: int = 20,
        lambda_mult: float = 0.5,
        filter: Optional[Dict[str, Any]] = None,
        **kwargs: Any,
    ) -> List[Document]:
        """Return docs selected using the maximal marginal relevance.
        Maximal marginal relevance optimizes for similarity to query AND diversity
        among selected documents.
        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 before filtering 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.