Vectara

Vectara 是一个用于构建基于 LLM 的应用程序的 API 平台。它提供了一个简单易用的文档索引和查询 API，由 Vectara 管理，并针对性能和准确性进行了优化。

这个笔记本展示了如何使用与 Vectara 向量数据库相关的功能。

有关如何使用 API 的更多信息，请参阅 Vectara API 文档。

我们希望使用 OpenAIEmbeddings，因此需要获取 OpenAI API 密钥。

import os
import getpass

os.environ['OPENAI_API_KEY'] = getpass.getpass('OpenAI API Key:')

OpenAI API Key:········

from langchain.embeddings.openai import OpenAIEmbeddings
from langchain.text_splitter import CharacterTextSplitter
from langchain.vectorstores import Vectara
from langchain.document_loaders import TextLoader

loader = TextLoader('../../../state_of_the_union.txt')
documents = loader.load()
text_splitter = CharacterTextSplitter(chunk_size=1000, chunk_overlap=0)
docs = text_splitter.split_documents(documents)

embeddings = OpenAIEmbeddings()

从 LangChain 连接到 Vectara

Vectara API 提供了用于索引和查询的简单 API 端点。

vectara = Vectara.from_documents(docs, embedding=None)

相似性搜索

使用 Vectara 的最简单场景是执行相似性搜索。

query = "What did the president say about Ketanji Brown Jackson"
found_docs = vectara.similarity_search(query, n_sentence_context=0)

print(found_docs[0].page_content)

Tonight. I call on the Senate to: Pass the Freedom to Vote Act. Pass the John Lewis Voting Rights Act. And while you’re at it, pass the Disclose Act so Americans can know who is funding our elections. 

Tonight, I’d like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the United States Supreme Court. Justice Breyer, thank you for your service. 

One of the most serious constitutional responsibilities a President has is nominating someone to serve on the United States Supreme Court. 

And I did that 4 days ago, when I nominated Circuit Court of Appeals Judge Ketanji Brown Jackson. One of our nation’s top legal minds, who will continue Justice Breyer’s legacy of excellence.

带有分数的相似性搜索

有时我们可能希望执行搜索，同时获取一个相关性分数，以了解特定结果的好坏程度。

query = "What did the president say about Ketanji Brown Jackson"
found_docs = vectara.similarity_search_with_score(query)

document, score = found_docs[0]
print(document.page_content)
print(f"\nScore: {score}")

Tonight. I call on the Senate to: Pass the Freedom to Vote Act. Pass the John Lewis Voting Rights Act. And while you’re at it, pass the Disclose Act so Americans can know who is funding our elections. 

Tonight, I’d like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the United States Supreme Court. Justice Breyer, thank you for your service. 

One of the most serious constitutional responsibilities a President has is nominating someone to serve on the United States Supreme Court. 

And I did that 4 days ago, when I nominated Circuit Court of Appeals Judge Ketanji Brown Jackson. One of our nation’s top legal minds, who will continue Justice Breyer’s legacy of excellence.

Score: 0.7129974

Vectara 作为检索器

Vectara 和其他向量存储一样，通过使用余弦相似度作为 LangChain 的检索器。

retriever = vectara.as_retriever()
retriever

VectaraRetriever(vectorstore=<langchain.vectorstores.vectara.Vectara object at 0x122db2830>, search_type='similarity', search_kwargs={'lambda_val': 0.025, 'k': 5, 'filter': '', 'n_sentence_context': '0'})

query = "What did the president say about Ketanji Brown Jackson"
retriever.get_relevant_documents(query)[0]

Document(page_content='Tonight. I call on the Senate to: Pass the Freedom to Vote Act. Pass the John Lewis Voting Rights Act. And while you’re at it, pass the Disclose Act so Americans can know who is funding our elections. \n\nTonight, I’d like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the United States Supreme Court. Justice Breyer, thank you for your service. \n\nOne of the most serious constitutional responsibilities a President has is nominating someone to serve on the United States Supreme Court. \n\nAnd I did that 4 days ago, when I nominated Circuit Court of Appeals Judge Ketanji Brown Jackson. One of our nation’s top legal minds, who will continue Justice Breyer’s legacy of excellence.', metadata={'source': '../../../state_of_the_union.txt'})