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Astra DB

DataStax Astra DB 是一个构建于 Apache Cassandra® 之上,通过易于使用的 JSON API 方便地提供的无服务器 AI 就绪数据库。

在本教程中,我们将演示使用 Astra DB 向量存储的 SelfQueryRetriever

创建 Astra DB 向量存储

首先,创建一个 Astra DB 向量存储并使用一些数据对其进行初始化。

我们创建了一个包含电影摘要的小型演示文档集。

注意:自查询检索器需要安装 `lark` 包(`pip install lark`)。

!pip install "langchain-astradb>=0.6,<0.7" \
"langchain_openai>=0.3,<0.4" \
"lark>=1.2,<2.0"

在此示例中,您将使用 OpenAIEmbeddings。请输入 OpenAI API 密钥。

import os
from getpass import getpass

from langchain_openai.embeddings import OpenAIEmbeddings

if "OPENAI_API_KEY" not in os.environ:
os.environ["OPENAI_API_KEY"] = getpass("OpenAI API Key:")

embeddings = OpenAIEmbeddings()
API 参考:OpenAIEmbeddings
OpenAI API Key: ········

创建 Astra DB VectorStore

  • API 端点类似于 https://01234567-89ab-cdef-0123-456789abcdef-us-east1.apps.astra.datastax.com
  • Token 类似于 AstraCS:aBcD0123...
ASTRA_DB_API_ENDPOINT = input("ASTRA_DB_API_ENDPOINT = ")
ASTRA_DB_APPLICATION_TOKEN = getpass("ASTRA_DB_APPLICATION_TOKEN = ")
ASTRA_DB_API_ENDPOINT =  https://01234567-89ab-cdef-0123-456789abcdef-us-east1.apps.astra.datastax.com
ASTRA_DB_APPLICATION_TOKEN = ········
from langchain_astradb import AstraDBVectorStore
from langchain_core.documents import Document

docs = [
Document(
page_content="A bunch of scientists bring back dinosaurs and mayhem breaks loose",
metadata={"year": 1993, "rating": 7.7, "genre": "science fiction"},
),
Document(
page_content="Leo DiCaprio gets lost in a dream within a dream within a dream within a ...",
metadata={"year": 2010, "director": "Christopher Nolan", "rating": 8.2},
),
Document(
page_content="A psychologist / detective gets lost in a series of dreams within dreams "
"within dreams and Inception reused the idea",
metadata={"year": 2006, "director": "Satoshi Kon", "rating": 8.6},
),
Document(
page_content="A bunch of normal-sized women are supremely wholesome and some men "
"pine after them",
metadata={"year": 2019, "director": "Greta Gerwig", "rating": 8.3},
),
Document(
page_content="Toys come alive and have a blast doing so",
metadata={"year": 1995, "genre": "animated"},
),
Document(
page_content="Three men walk into the Zone, three men walk out of the Zone",
metadata={
"year": 1979,
"director": "Andrei Tarkovsky",
"genre": "science fiction",
"rating": 9.9,
},
),
]

vectorstore = AstraDBVectorStore.from_documents(
docs,
embeddings,
collection_name="astra_self_query_demo",
api_endpoint=ASTRA_DB_API_ENDPOINT,
token=ASTRA_DB_APPLICATION_TOKEN,
)

创建自查询检索器

现在您可以实例化该检索器。

为此,您需要预先提供有关文档支持的元数据字段的一些信息,以及文档内容的简短描述。

from langchain.chains.query_constructor.schema import AttributeInfo
from langchain.retrievers.self_query.base import SelfQueryRetriever
from langchain_openai import OpenAI

metadata_field_info = [
AttributeInfo(
name="genre",
description="The genre of the movie",
type="string or list[string]",
),
AttributeInfo(
name="year",
description="The year the movie was released",
type="integer",
),
AttributeInfo(
name="director",
description="The name of the movie director",
type="string",
),
AttributeInfo(
name="rating", description="A 1-10 rating for the movie", type="float"
),
]
document_content_description = "Brief summary of a movie"
llm = OpenAI(temperature=0)

retriever = SelfQueryRetriever.from_llm(
llm,
vectorstore,
document_content_description,
metadata_field_info,
verbose=True,
)

试用

现在您可以尝试实际使用我们的检索器

# This example only specifies a relevant query
retriever.invoke("What are some movies about dinosaurs?")
[Document(id='d7b9ec1edafa467caab524455e8c1f5d', metadata={'year': 1993, 'rating': 7.7, 'genre': 'science fiction'}, page_content='A bunch of scientists bring back dinosaurs and mayhem breaks loose'),
Document(id='8ad04ef2a73d4f74897a51e49be1a8d2', metadata={'year': 1995, 'genre': 'animated'}, page_content='Toys come alive and have a blast doing so'),
Document(id='5b07e600d3494506952b60e0a45a0546', metadata={'year': 1979, 'director': 'Andrei Tarkovsky', 'genre': 'science fiction', 'rating': 9.9}, page_content='Three men walk into the Zone, three men walk out of the Zone'),
Document(id='a0cef19e27c341929098ac4793602829', metadata={'year': 2006, 'director': 'Satoshi Kon', 'rating': 8.6}, page_content='A psychologist / detective gets lost in a series of dreams within dreams within dreams and Inception reused the idea')]
# This example specifies a filter
retriever.invoke("I want to watch a movie rated higher than 8.5")
[Document(id='5b07e600d3494506952b60e0a45a0546', metadata={'year': 1979, 'director': 'Andrei Tarkovsky', 'genre': 'science fiction', 'rating': 9.9}, page_content='Three men walk into the Zone, three men walk out of the Zone'),
Document(id='a0cef19e27c341929098ac4793602829', metadata={'year': 2006, 'director': 'Satoshi Kon', 'rating': 8.6}, page_content='A psychologist / detective gets lost in a series of dreams within dreams within dreams and Inception reused the idea')]
# This example only specifies a query and a filter
retriever.invoke("Has Greta Gerwig directed any movies about women")
[Document(id='0539843fd203484c9be486c2a0e2454c', metadata={'year': 2019, 'director': 'Greta Gerwig', 'rating': 8.3}, page_content='A bunch of normal-sized women are supremely wholesome and some men pine after them')]
# This example specifies a composite filter
retriever.invoke("What's a highly rated (above 8.5), science fiction movie ?")
[Document(id='a0cef19e27c341929098ac4793602829', metadata={'year': 2006, 'director': 'Satoshi Kon', 'rating': 8.6}, page_content='A psychologist / detective gets lost in a series of dreams within dreams within dreams and Inception reused the idea'),
Document(id='5b07e600d3494506952b60e0a45a0546', metadata={'year': 1979, 'director': 'Andrei Tarkovsky', 'genre': 'science fiction', 'rating': 9.9}, page_content='Three men walk into the Zone, three men walk out of the Zone')]
# This example specifies a query and composite filter
retriever.invoke(
"What's a movie about toys after 1990 but before 2005, and is animated"
)
[Document(id='8ad04ef2a73d4f74897a51e49be1a8d2', metadata={'year': 1995, 'genre': 'animated'}, page_content='Toys come alive and have a blast doing so')]

设置限制 ('k')

您还可以使用自查询检索器来指定 k,即要获取的文档数量。

通过向构造函数传递 enable_limit=True 即可实现此目的。

retriever_k = SelfQueryRetriever.from_llm(
llm,
vectorstore,
document_content_description,
metadata_field_info,
verbose=True,
enable_limit=True,
)
# This example only specifies a relevant query
retriever_k.invoke("What are two movies about dinosaurs?")
[Document(id='d7b9ec1edafa467caab524455e8c1f5d', metadata={'year': 1993, 'rating': 7.7, 'genre': 'science fiction'}, page_content='A bunch of scientists bring back dinosaurs and mayhem breaks loose'),
Document(id='8ad04ef2a73d4f74897a51e49be1a8d2', metadata={'year': 1995, 'genre': 'animated'}, page_content='Toys come alive and have a blast doing so')]

清理

如果您想从 Astra DB 实例中完全删除集合,请运行此命令。

(您将丢失其中存储的数据。)

vectorstore.delete_collection()