community: add top_k as param to Needle Retriever

[JANHMS]

Thank you for contributing to LangChain!

• PR title: "package: description"

  • Where "package" is whichever of langchain, community, core, etc. is being modified. Use "docs: ..." for purely docs changes, "infra: ..." for CI changes.
  • Example: "community: add foobar LLM"

• PR message:
  This PR adds top_k as a param to the Needle Retriever. By default we use top 10.

• Add tests and docs: If you're adding a new integration, please include

  1. a test for the integration, preferably unit tests that do not rely on network access,
  2. an example notebook showing its use. It lives in docs/docs/integrations directory.

• Lint and test: Run make format, make lint and make test from the root of the package(s) you've modified. See contribution guidelines for more: https://python.langchain.com/docs/contributing/

Additional guidelines:

• Make sure optional dependencies are imported within a function.
• Please do not add dependencies to pyproject.toml files (even optional ones) unless they are required for unit tests.
• Most PRs should not touch more than one package.
• Changes should be backwards compatible.
• If you are adding something to community, do not re-import it in langchain.

If no one reviews your PR within a few days, please @-mention one of baskaryan, efriis, eyurtsev, ccurme, vbarda, hwchase17.

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
langchain	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Feb 16, 2025 10:27am

[JANHMS]

@efriis Hey man, adding a small detail here. Should be an easy to merge PR. Just adding the top_k to the Needle retriever.

[ccurme]

Why not set default as None, as in the client?

Won't this change behavior for existing users?

[JANHMS]

Yes you are right. I will adjust, appreciate the comment.