跳至主要内容

优化

优化文档链通过循环遍历输入文档并迭代更新其答案来构建响应。对于每个文档，它将所有非文档输入、当前文档和最新的中间答案传递给 LLM 链，以获取新的答案。

由于优化链每次只将单个文档传递给 LLM，因此它非常适合需要分析超出模型上下文容量的更多文档的任务。明显的权衡是，与例如填充文档链相比，此链将进行更多的 LLM 调用。某些任务也难以迭代完成。例如，当文档频繁交叉引用或任务需要来自许多文档的详细信息时，优化链的性能可能会很差。

refine_diagram

以下是实际应用中的示例

提示

请参阅 此部分，了解安装集成包的通用说明。

npm install @langchain/openai
import { loadQARefineChain } from "langchain/chains";
import { OpenAI, OpenAIEmbeddings } from "@langchain/openai";
import { TextLoader } from "langchain/document_loaders/fs/text";
import { MemoryVectorStore } from "langchain/vectorstores/memory";

// Create the models and chain
const embeddings = new OpenAIEmbeddings();
const model = new OpenAI({ temperature: 0 });
const chain = loadQARefineChain(model);

// Load the documents and create the vector store
const loader = new TextLoader("./state_of_the_union.txt");
const docs = await loader.loadAndSplit();
const store = await MemoryVectorStore.fromDocuments(docs, embeddings);

// Select the relevant documents
const question = "What did the president say about Justice Breyer";
const relevantDocs = await store.similaritySearch(question);

// Call the chain
const res = await chain.invoke({
  input_documents: relevantDocs,
  question,
});

console.log(res);
/*
{
  output_text: '\n' +
    '\n' +
    "The president said that Justice Stephen Breyer has dedicated his life to serve this country and thanked him for his service. He also mentioned that Judge Ketanji Brown Jackson will continue Justice Breyer's legacy of excellence, and that the constitutional right affirmed in Roe v. Wade—standing precedent for half a century—is under attack as never before. He emphasized the importance of protecting access to health care, preserving a woman's right to choose, and advancing maternal health care in America. He also expressed his support for the LGBTQ+ community, and his commitment to protecting their rights, including offering a Unity Agenda for the Nation to beat the opioid epidemic, increase funding for prevention, treatment, harm reduction, and recovery, and strengthen the Violence Against Women Act."
}
*/

API 参考

提示自定义​

您可能希望通过更改提示来调整步骤的行为。以下是如何执行此操作的示例

import { loadQARefineChain } from "langchain/chains";
import { OpenAI, OpenAIEmbeddings } from "@langchain/openai";
import { TextLoader } from "langchain/document_loaders/fs/text";
import { MemoryVectorStore } from "langchain/vectorstores/memory";
import { PromptTemplate } from "@langchain/core/prompts";

export const questionPromptTemplateString = `Context information is below.
---------------------
{context}
---------------------
Given the context information and no prior knowledge, answer the question: {question}`;

const questionPrompt = new PromptTemplate({
  inputVariables: ["context", "question"],
  template: questionPromptTemplateString,
});

const refinePromptTemplateString = `The original question is as follows: {question}
We have provided an existing answer: {existing_answer}
We have the opportunity to refine the existing answer
(only if needed) with some more context below.
------------
{context}
------------
Given the new context, refine the original answer to better answer the question.
You must provide a response, either original answer or refined answer.`;

const refinePrompt = new PromptTemplate({
  inputVariables: ["question", "existing_answer", "context"],
  template: refinePromptTemplateString,
});

// Create the models and chain
const embeddings = new OpenAIEmbeddings();
const model = new OpenAI({ temperature: 0 });
const chain = loadQARefineChain(model, {
  questionPrompt,
  refinePrompt,
});

// Load the documents and create the vector store
const loader = new TextLoader("./state_of_the_union.txt");
const docs = await loader.loadAndSplit();
const store = await MemoryVectorStore.fromDocuments(docs, embeddings);

// Select the relevant documents
const question = "What did the president say about Justice Breyer";
const relevantDocs = await store.similaritySearch(question);

// Call the chain
const res = await chain.invoke({
  input_documents: relevantDocs,
  question,
});

console.log(res);
/*
{
  output_text: '\n' +
    '\n' +
    "The president said that Justice Stephen Breyer has dedicated his life to serve this country and thanked him for his service. He also mentioned that Judge Ketanji Brown Jackson will continue Justice Breyer's legacy of excellence, and that the constitutional right affirmed in Roe v. Wade—standing precedent for half a century—is under attack as never before. He emphasized the importance of protecting access to health care, preserving a woman's right to choose, and advancing maternal health care in America. He also expressed his support for the LGBTQ+ community, and his commitment to protecting their rights, including offering a Unity Agenda for the Nation to beat the opioid epidemic, increase funding for prevention, treatment, harm reduction, and recovery, and strengthen the Violence Against Women Act."
}
*/

API 参考

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