feat(community): Port ArxivRetriever to LangChainJS

docs/core_docs/docs/integrations/retrievers/arxiv-retriever.mdx

@@ -0,0 +1,99 @@
+# ArxivRetriever
+
+The `arXiv Retriever` allows users to query the arXiv database for academic articles. It supports both full-document retrieval (PDF parsing) and summary-based retrieval.
+
+For detailed documentation of all ArxivRetriever features and configurations, head to the [API reference](https://api.js.langchain.com/classes/_langchain_community.retrievers_arxiv.ArxivRetriever.html)
+
+## Features
+
+- Query Flexibility: Search using natural language queries or specific arXiv IDs.
+- Full-Document Retrieval: Option to fetch and parse PDFs.
+- Summaries as Documents: Retrieve summaries for faster results.
+- Customizable Options: Configure maximum results and output format.
+
+## Integration details
+
+| Retriever        | Source                       | Package                                                                      |
+| ---------------- | ---------------------------- | ---------------------------------------------------------------------------- |
+| `ArxivRetriever` | Academic articles from arXiv | [`@langchain/community`](https://www.npmjs.com/package/@langchain/community) |
+
+## Setup
+
+Ensure the following dependencies are installed:
+
+- `pdf-parse` for parsing PDFs
+- `fast-xml-parser` for parsing XML responses from the arXiv API
+
+```npm2yarn
+npm install pdf-parse fast-xml-parser
+```
+
+## Instantiation
+
+```typescript
+const retriever = new ArxivRetriever({
+  getFullDocuments: false, // Set to true to fetch full documents (PDFs)
+  maxSearchResults: 5, // Maximum number of results to retrieve
+});
+```
+
+## Usage
+
+Use the `invoke` method to search arXiv for relevant articles. You can use either natural language queries or specific arXiv IDs.
+
+```typescript
+const query = "quantum computing";
+
+const documents = await retriever.invoke(query);
+documents.forEach((doc) => {
+  console.log("Title:", doc.metadata.title);
+  console.log("Content:", doc.pageContent); // Parsed PDF content
+});
+```
+
+## Use within a chain
+
+Like other retrievers, `ArxivRetriever` can be incorporated into LLM applications via chains. Below is an example of using the retriever within a chain:
+
+```typescript
+import { ChatOpenAI } from "@langchain/openai";
+import { ChatPromptTemplate } from "@langchain/core/prompts";
+import {
+  RunnablePassthrough,
+  RunnableSequence,
+} from "@langchain/core/runnables";
+import { StringOutputParser } from "@langchain/core/output_parsers";
+import type { Document } from "@langchain/core/documents";
+
+const llm = new ChatOpenAI({
+  model: "gpt-4o-mini",
+  temperature: 0,
+});
+
+const prompt = ChatPromptTemplate.fromTemplate(`
+Answer the question based only on the context provided.
+
+Context: {context}
+
+Question: {question}`);
+
+const formatDocs = (docs: Document[]) => {
+  return docs.map((doc) => doc.pageContent).join("\n\n");
+};
+
+const ragChain = RunnableSequence.from([
+  {
+    context: retriever.pipe(formatDocs),
+    question: new RunnablePassthrough(),
+  },
+  prompt,
+  llm,
+  new StringOutputParser(),
+]);
+
+await ragChain.invoke("What are the latest advances in quantum computing?");
+```
+
+## API reference
+
+For detailed documentation of all ArxivRetriever features and configurations, head to the [API reference](https://api.js.langchain.com/classes/_langchain_community.retrievers_arxiv.ArxivRetriever.html)

examples/src/retrievers/arxiv.ts

@@ -0,0 +1,65 @@
+import { ArxivRetriever } from "@langchain/community/retrievers/arxiv";
+
+export const run = async () => {
+  /*
+    Direct look up by arXiv ID, for full texts
+  */
+
+  const queryId = "1605.08386 2103.03404";
+  const retrieverById = new ArxivRetriever({
+    getFullDocuments: true,
+    maxSearchResults: 5,
+  });
+  const documentsById = await retrieverById.invoke(queryId);
+  console.log(documentsById);
+
+  /*
+  [
+    Document
+    {
+      pageContent,
+      metadata: 
+      {
+        author,
+        id,
+        published,
+        source,
+        updated,
+        url
+      }
+    },
+    Document
+    {
+      pageContent,
+      metadata
+    }
+  ]
+  */
+
+  /*
+  Search with natural language query, for summaries
+  */
+
+  const queryNat = "What is the ImageBind model?";
+  const retrieverByNat = new ArxivRetriever({
+    getFullDocuments: false,
+    maxSearchResults: 2,
+  });
+  const documentsByQuery = await retrieverByNat.invoke(queryNat);
+  console.log(documentsByQuery);
+
+  /*
+  [
+    Document
+    {
+      pageContent,
+      metadata
+    },
+    Document
+    {
+      pageContent,
+      metadata
+    }
+  ]
+  */
+};

libs/langchain-community/.gitignore

@@ -626,6 +626,10 @@ retrievers/amazon_knowledge_base.cjs
 retrievers/amazon_knowledge_base.js
 retrievers/amazon_knowledge_base.d.ts
 retrievers/amazon_knowledge_base.d.cts
+retrievers/arxiv.cjs
+retrievers/arxiv.js
+retrievers/arxiv.d.ts
+retrievers/arxiv.d.cts
 retrievers/bm25.cjs
 retrievers/bm25.js
 retrievers/bm25.d.ts

libs/langchain-community/langchain.config.js

@@ -198,6 +198,7 @@ export const config = {
     // retrievers
     "retrievers/amazon_kendra": "retrievers/amazon_kendra",
     "retrievers/amazon_knowledge_base": "retrievers/amazon_knowledge_base",
+    "retrievers/arxiv": "retrievers/arxiv",
     "retrievers/bm25": "retrievers/bm25",
     "retrievers/chaindesk": "retrievers/chaindesk",
     "retrievers/databerry": "retrievers/databerry",
@@ -437,6 +438,7 @@ export const config = {
     "chat_models/zhipuai",
     "retrievers/amazon_kendra",
     "retrievers/amazon_knowledge_base",
+    "retrievers/arxiv",
     "retrievers/dria",
     "retrievers/metal",
     "retrievers/supabase",

libs/langchain-community/package.json

@@ -166,6 +166,7 @@
     "eslint-plugin-no-instanceof": "^1.0.1",
     "eslint-plugin-prettier": "^4.2.1",
     "faiss-node": "^0.5.1",
+    "fast-xml-parser": "^4.5.1",
     "firebase-admin": "^11.9.0 || ^12.0.0",
     "google-auth-library": "^9.10.0",
     "googleapis": "^126.0.1",
@@ -302,6 +303,7 @@
     "duck-duck-scrape": "^2.2.5",
     "epub2": "^3.0.1",
     "faiss-node": "^0.5.1",
+    "fast-xml-parser": "*",
     "firebase-admin": "^11.9.0 || ^12.0.0",
     "google-auth-library": "*",
     "googleapis": "*",
@@ -584,6 +586,9 @@
     "faiss-node": {
       "optional": true
     },
+    "fast-xml-parser": {
+      "optional": true
+    },
     "firebase-admin": {
       "optional": true
     },
@@ -2125,6 +2130,15 @@
       "import": "./retrievers/amazon_knowledge_base.js",
       "require": "./retrievers/amazon_knowledge_base.cjs"
     },
+    "./retrievers/arxiv": {
+      "types": {
+        "import": "./retrievers/arxiv.d.ts",
+        "require": "./retrievers/arxiv.d.cts",
+        "default": "./retrievers/arxiv.d.ts"
+      },
+      "import": "./retrievers/arxiv.js",
+      "require": "./retrievers/arxiv.cjs"
+    },
     "./retrievers/bm25": {
       "types": {
         "import": "./retrievers/bm25.d.ts",
@@ -3774,6 +3788,10 @@
     "retrievers/amazon_knowledge_base.js",
     "retrievers/amazon_knowledge_base.d.ts",
     "retrievers/amazon_knowledge_base.d.cts",
+    "retrievers/arxiv.cjs",
+    "retrievers/arxiv.js",
+    "retrievers/arxiv.d.ts",
+    "retrievers/arxiv.d.cts",
     "retrievers/bm25.cjs",
     "retrievers/bm25.js",
     "retrievers/bm25.d.ts",

libs/langchain-community/src/load/import_constants.ts

@@ -100,6 +100,7 @@ export const optionalImportEntrypoints: string[] = [
   "langchain_community/callbacks/handlers/upstash_ratelimit",
   "langchain_community/retrievers/amazon_kendra",
   "langchain_community/retrievers/amazon_knowledge_base",
+  "langchain_community/retrievers/arxiv",
   "langchain_community/retrievers/dria",
   "langchain_community/retrievers/metal",
   "langchain_community/retrievers/supabase",

libs/langchain-community/src/retrievers/arxiv.ts

@@ -0,0 +1,50 @@
+import { BaseRetriever, BaseRetrieverInput } from "@langchain/core/retrievers";
+import { Document } from "@langchain/core/documents";
+import {
+  searchArxiv,
+  loadDocsFromResults,
+  getDocsFromSummaries,
+} from "../utils/arxiv.js";
+
+export type ArxivRetrieverOptions = {
+  getFullDocuments?: boolean;
+  maxSearchResults?: number;
+} & BaseRetrieverInput;
+
+/**
+ * A retriever that searches arXiv for relevant articles based on a query.
+ * It can retrieve either full documents (PDFs) or just summaries.
+ */
+export class ArxivRetriever extends BaseRetriever {
+  static lc_name() {
+    return "ArxivRetriever";
+  }
+
+  lc_namespace = ["langchain", "retrievers", "arxiv_retriever"];
+
+  getFullDocuments = false;
+
+  maxSearchResults = 10;
+
+  constructor(options: ArxivRetrieverOptions = {}) {
+    super(options);
+    this.getFullDocuments = options.getFullDocuments ?? this.getFullDocuments;
+    this.maxSearchResults = options.maxSearchResults ?? this.maxSearchResults;
+  }
+
+  async _getRelevantDocuments(query: string): Promise<Document[]> {
+    try {
+      const results = await searchArxiv(query, this.maxSearchResults);
+
+      if (this.getFullDocuments) {
+        // Fetch and parse PDFs to get full documents
+        return await loadDocsFromResults(results);
+      } else {
+        // Use summaries as documents
+        return getDocsFromSummaries(results);
+      }
+    } catch (error) {
+      throw new Error(`Error retrieving documents from arXiv.`);
+    }
+  }
+}