LostInTheMiddleRanker

A LostInTheMiddle Ranker.

Basic Information

• Type: haystack_integrations.rankers.lost_in_the_middle.LostInTheMiddleRanker

Inputs

Parameter	Type	Default	Description
documents	List[Document]		List of Documents to reorder.
top_k	Optional[int]	None	The maximum number of documents to return.
word_count_threshold	Optional[int]	None	The maximum total number of words across all documents selected by the ranker.

Outputs

Parameter	Type	Default	Description
documents	List[Document]		A dictionary with the following keys: - documents: Reranked list of Documents

Overview

Work in Progress

Bear with us while we're working on adding pipeline examples and most common components connections.

A LostInTheMiddle Ranker.

Ranks documents based on the 'lost in the middle' order so that the most relevant documents are either at the beginning or end, while the least relevant are in the middle.

LostInTheMiddleRanker assumes that some prior component in the pipeline has already ranked documents by relevance and requires no query as input but only documents. It is typically used as the last component before building a prompt for an LLM to prepare the input context for the LLM.

Lost in the Middle ranking lays out document contents into LLM context so that the most relevant contents are at the beginning or end of the input context, while the least relevant is in the middle of the context. See the paper "Lost in the Middle: How Language Models Use Long Contexts" for more details.

Usage example:

from haystack.components.rankers import LostInTheMiddleRanker
from haystack import Document

ranker = LostInTheMiddleRanker()
docs = [Document(content="Paris"), Document(content="Berlin"), Document(content="Madrid")]
result = ranker.run(documents=docs)
for doc in result["documents"]:
    print(doc.content)

Usage Example

components:
  LostInTheMiddleRanker:
    type: components.rankers.lost_in_the_middle.LostInTheMiddleRanker
    init_parameters:

Parameters

Init Parameters

These are the parameters you can configure in Pipeline Builder:

Parameter	Type	Default	Description
word_count_threshold	Optional[int]	None	The maximum total number of words across all documents selected by the ranker.
top_k	Optional[int]	None	The maximum number of documents to return.

Run Method Parameters

These are the parameters you can configure for the component's run() method. This means you can pass these parameters at query time through the API, in Playground, or when running a job. For details, see Modify Pipeline Parameters at Query Time.

Parameter	Type	Default	Description
documents	List[Document]		List of Documents to reorder.
top_k	Optional[int]	None	The maximum number of documents to return.
word_count_threshold	Optional[int]	None	The maximum total number of words across all documents selected by the ranker.