🦜️🔗 LangChain.js Semantic Length Example Selector

When you want to provide examples as context for a LLM you can use LangChain.js "Select by length" or "Select by similarity" Prompt Selectors. However what if you need to select by similarity while ensuring a max length? This package solves that issue by combining the LengthBasedExampleSelector and the SemanticSimilarityExampleSelector into the SemanticLengthExampleSelector.

Install package

yarn add whitesmith/langchain-semantic-length-example-selector

Usage

import { SemanticLengthExampleSelector, getLengthBased } from '@whitesmith/langchain-semantic-length-example-selector';

// ...

const promptPrefix = "Generate ... using the below examples as reference:";
const promptSuffix = "You are ... ";
const examplePrompt = PromptTemplate.fromTemplate("<example>{content}</example>");

const embeddings = new OpenAIEmbeddings();
const vectorStore = new MemoryVectorStore(embeddings);

// ...

const exampleSelector = new SemanticLengthExampleSelector({
  vectorStore: vectorStore,
  k: 6, // return up to 6 most similar examples
  inputKeys: ["content"],
  examplePrompt: examplePrompt,
  // prompt max length in words
  maxLength: 50 - getLengthBased(promptPrefix) - getLengthBased(promptSuffix)
});

const dynamicPrompt = new FewShotPromptTemplate({
  exampleSelector,
  examplePrompt,
  prefix: promptPrefix,
  suffix: promptSuffix,
  inputVariables: ["content"],
});

// ...

// For testing purposes
const formattedValue = await dynamicPrompt.format({
  content: "...",
});
console.log(formattedValue);

// ...

const model = new ChatOpenAI(...);
const chain = dynamicPrompt.pipe(model);

const result = await chain.invoke({ content: exampleContent });
console.log(result.content);

For a full example check the file in /examples/index.js (link)

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Development

Run

yarn build

Test the package

You can test the code with Jest

yarn test

You can find the test coverage in coverage/lcov-report/index.html.

Check dependencies

You can check and upgrade dependencies to the latest versions, ignoring specified versions. with npm-check-updates:

yarn run check-updates

You can also use npm run check-updates:minor to update only patch and minor.

Instead npm run check-updates:patch only updates patch.

Publish

First commit the changes to GitHub. Then login to your NPM account (If you don’t have an account you can do so on https://www.npmjs.com/signup)

npm login

Then run publish:

npm publish

If you're using a scoped name use:

npm publish --access public

Bumping a new version

To update the package use:

npm version patch

and then

npm publish

Thank you to @el3um4s for the @el3um4s/typescript-npm-package-starter.