如何重新排序检索结果以减轻“中间丢失”效应

%pip install -qU langchain langchain-community langchain-openai

from langchain_core.vectorstores import InMemoryVectorStore
from langchain_openai import OpenAIEmbeddings

# Get embeddings.
embeddings = OpenAIEmbeddings()

texts = [
    "Basquetball is a great sport.",
    "Fly me to the moon is one of my favourite songs.",
    "The Celtics are my favourite team.",
    "This is a document about the Boston Celtics",
    "I simply love going to the movies",
    "The Boston Celtics won the game by 20 points",
    "This is just a random text.",
    "Elden Ring is one of the best games in the last 15 years.",
    "L. Kornet is one of the best Celtics players.",
    "Larry Bird was an iconic NBA player.",
]

# Create a retriever
retriever = InMemoryVectorStore.from_texts(texts, embedding=embeddings).as_retriever(
    search_kwargs={"k": 10}
)
query = "What can you tell me about the Celtics?"

# Get relevant documents ordered by relevance score
docs = retriever.invoke(query)
for doc in docs:
    print(f"- {doc.page_content}")

from langchain_community.document_transformers import LongContextReorder

# Reorder the documents:
# Less relevant document will be at the middle of the list and more
# relevant elements at beginning / end.
reordering = LongContextReorder()
reordered_docs = reordering.transform_documents(docs)

# Confirm that the 4 relevant documents are at beginning and end.
for doc in reordered_docs:
    print(f"- {doc.page_content}")

from langchain.chains.combine_documents import create_stuff_documents_chain
from langchain_core.prompts import PromptTemplate
from langchain_openai import ChatOpenAI

llm = ChatOpenAI(model="gpt-4o-mini")

prompt_template = """
Given these texts:
-----
{context}
-----
Please answer the following question:
{query}
"""

prompt = PromptTemplate(
    template=prompt_template,
    input_variables=["context", "query"],
)

# Create and invoke the chain:
chain = create_stuff_documents_chain(llm, prompt)
response = chain.invoke({"context": reordered_docs, "query": query})
print(response)