在本示例中，我们将演示如何组合来自多个查询和多个索引的检索结果。

检索到的节点将作为所有查询和索引中的前 k 个节点返回，并会处理任何节点的去重。

import os
import openai

os.environ["OPENAI_API_KEY"] = "sk-..."
openai.api_key = os.environ["OPENAI_API_KEY"]

设置

对于本 notebook，我们将使用文档中两个非常相似的页面，每个页面存储在单独的索引中。

from llama_index.core import SimpleDirectoryReader

documents_1 = SimpleDirectoryReader(
    input_files=["../../community/integrations/vector_stores.md"]
).load_data()
documents_2 = SimpleDirectoryReader(
    input_files=["../../module_guides/storing/vector_stores.md"]
).load_data()

from llama_index.core import VectorStoreIndex

index_1 = VectorStoreIndex.from_documents(documents_1)
index_2 = VectorStoreIndex.from_documents(documents_2)

融合索引！

在这一步中，我们将索引融合到单个检索器中。该检索器还将通过生成与原始问题相关的额外查询来增强我们的查询，并聚合结果。

此设置还将查询 4 次：一次使用你的原始查询，并生成另外 3 个查询。

默认情况下，它使用以下提示词生成额外查询：

QUERY_GEN_PROMPT = (
    "You are a helpful assistant that generates multiple search queries based on a "
    "single input query. Generate {num_queries} search queries, one on each line, "
    "related to the following input query:\n"
    "Query: {query}\n"
    "Queries:\n"
)

from llama_index.core.retrievers import QueryFusionRetriever

retriever = QueryFusionRetriever(
    [index_1.as_retriever(), index_2.as_retriever()],
    similarity_top_k=2,
    num_queries=4,  # set this to 1 to disable query generation
    use_async=True,
    verbose=True,
    # query_gen_prompt="...",  # we could override the query generation prompt here
)

# apply nested async to run in a notebook
import nest_asyncio

nest_asyncio.apply()

nodes_with_scores = retriever.retrieve("How do I setup a chroma vector store?")

Generated queries:
1. What are the steps to set up a chroma vector store?
2. Best practices for configuring a chroma vector store
3. Troubleshooting common issues when setting up a chroma vector store

for node in nodes_with_scores:
    print(f"Score: {node.score:.2f} - {node.text[:100]}...")

Score: 0.78 - # Vector Stores

Vector stores contain embedding vectors of ingested document chunks
(and sometimes ...
Score: 0.78 - # Using Vector Stores

LlamaIndex offers multiple integration points with vector stores / vector dat...

在查询引擎中使用！

现在，我们可以将检索器接入查询引擎，以合成自然语言响应。

from llama_index.core.query_engine import RetrieverQueryEngine

query_engine = RetrieverQueryEngine.from_args(retriever)

response = query_engine.query(
    "How do I setup a chroma vector store? Can you give an example?"
)

Generated queries:
1. How to set up a chroma vector store?
2. Step-by-step guide for creating a chroma vector store.
3. Examples of chroma vector store setups and configurations.

from llama_index.core.response.notebook_utils import display_response

display_response(response)

最终响应： 要设置 Chroma 向量存储，你需要遵循以下步骤：

1. 导入必要的库：

import chromadb
from llama_index.vector_stores.chroma import ChromaVectorStore

2. 创建 Chroma 客户端：

chroma_client = chromadb.EphemeralClient()
chroma_collection = chroma_client.create_collection("quickstart")

3. 构造向量存储：

vector_store = ChromaVectorStore(chroma_collection=chroma_collection)

以下是使用上述步骤设置 Chroma 向量存储的示例：

import chromadb
from llama_index.vector_stores.chroma import ChromaVectorStore

# Creating a Chroma client
# EphemeralClient operates purely in-memory, PersistentClient will also save to disk
chroma_client = chromadb.EphemeralClient()
chroma_collection = chroma_client.create_collection("quickstart")

# construct vector store
vector_store = ChromaVectorStore(chroma_collection=chroma_collection)

本示例演示如何创建 Chroma 客户端、创建名为“quickstart”的集合，然后使用该集合构造 Chroma 向量存储。