Fleet Context Embeddings - 为Llamaindex库构建混合搜索引擎

在本指南中，我们将使用 Fleet Context 下载 LlamaIndex 文档的嵌入向量，并基于此构建一个混合稠密/稀疏向量检索引擎。

先决条件

!pip install llama-index
!pip install --upgrade fleet-context

import os
import openai

os.environ["OPENAI_API_KEY"] = "sk-..." # add your API key here!
openai.api_key = os.environ["OPENAI_API_KEY"]

从 Fleet Context 下载嵌入向量

我们将使用 Fleet Context 下载整个 LlamaIndex 文档的嵌入向量（约1.2万个文本块，约100MB内容）。您可以通过指定库名称作为参数，下载前1220个热门库中任意一个的嵌入。您可以在页面底部此处查看支持的完整库列表。

我们这样做是因为 Fleet 构建了一个嵌入管道，能够保留许多重要信息，这些信息将提升检索和生成效果，包括页面位置（用于重新排序）、区块类型（类/函数/属性等）、父级章节等更多内容。您可以在他们的Github 页面上了解更多相关信息。

from context import download_embeddings

df = download_embeddings("llamaindex")

输出：

    100%|██████████| 83.7M/83.7M [00:03<00:00, 27.4MiB/s]
                                         id  \
    0  e268e2a1-9193-4e7b-bb9b-7a4cb88fc735
    1  e495514b-1378-4696-aaf9-44af948de1a1
    2  e804f616-7db0-4455-9a06-49dd275f3139
    3  eb85c854-78f1-4116-ae08-53b2a2a9fa41
    4  edfc116e-cf58-4118-bad4-c4bc0ca1495e

# Show some examples of the metadata
df["metadata"][0]
display(Markdown(f"{df['metadata'][8000]['text']}"))

输出：

classmethod from_dict(data: Dict[str, Any], kwargs: Any) → Self classmethod from_json(data_str: str, kwargs: Any) → Self classmethod from_orm(obj: Any) → Model json(, include: Optional[Union[AbstractSetIntStr, MappingIntStrAny]] = None, exclude: Optional[Union[AbstractSetIntStr, MappingIntStrAny]] = None, by_alias: bool = False, skip_defaults: Optional[bool] = None, exclude_unset: bool = False, exclude_defaults: bool = False, exclude_none: bool = False, encoder: Optional[Callable[[Any], Any]] = None, models_as_dict: bool = True*, dumps_kwargs: Any) → unicode Generate a JSON representation of the model, include and exclude arguments as per dict().

在LlamaIndex中为混合搜索创建Pinecone索引

我们将创建一个Pinecone索引并在其中上传向量，以便能够同时使用稀疏向量和密集向量进行混合检索。请确保您已拥有Pinecone账户再继续操作。

import logging
import sys

logging.basicConfig(stream=sys.stdout, level=logging.INFO)
logging.getLogger().handlers = []
logging.getLogger().addHandler(logging.StreamHandler(stream=sys.stdout))

import pinecone

api_key = "..."  # Add your Pinecone API key here
pinecone.init(
    api_key=api_key, environment="us-east-1-aws"
)  # Add your db region here

# Fleet Context uses the text-embedding-ada-002 model from OpenAI with 1536 dimensions.

# NOTE: Pinecone requires dotproduct similarity for hybrid search
pinecone.create_index(
    "quickstart-fleet-context",
    dimension=1536,
    metric="dotproduct",
    pod_type="p1",
)

pinecone.describe_index(
    "quickstart-fleet-context"
)  # Make sure you create an index in pinecone

from llama_index.vector_stores.pinecone import PineconeVectorStore

pinecone_index = pinecone.Index("quickstart-fleet-context")
vector_store = PineconeVectorStore(pinecone_index, add_sparse_vector=True)

批量将向量更新插入到Pinecone

Pinecone建议每次上传100个向量。我们将在稍微修改数据格式后执行此操作。

import random
import itertools


def chunks(iterable, batch_size=100):
    """A helper function to break an iterable into chunks of size batch_size."""
    it = iter(iterable)
    chunk = tuple(itertools.islice(it, batch_size))
    while chunk:
        yield chunk
        chunk = tuple(itertools.islice(it, batch_size))


# generator that generates many (id, vector, metadata, sparse_values) pairs
data_generator = map(
    lambda row: {
        "id": row[1]["id"],
        "values": row[1]["values"],
        "metadata": row[1]["metadata"],
        "sparse_values": row[1]["sparse_values"],
    },
    df.iterrows(),
)

# Upsert data with 1000 vectors per upsert request
for ids_vectors_chunk in chunks(data_generator, batch_size=100):
    print(f"Upserting {len(ids_vectors_chunk)} vectors...")
    pinecone_index.upsert(vectors=ids_vectors_chunk)

在LlamaIndex中构建Pinecone向量存储

最后，我们将通过LlamaIndex构建Pinecone向量存储并查询它以获取结果。

from llama_index.core import VectorStoreIndex
from IPython.display import Markdown, display

index = VectorStoreIndex.from_vector_store(vector_store=vector_store)

查询您的索引！

query_engine = index.as_query_engine(
    vector_store_query_mode="hybrid", similarity_top_k=8
)
response = query_engine.query("How do I use llama_index SimpleDirectoryReader")

display(Markdown(f"<b>{response}</b>"))

输出：

<b>To use the SimpleDirectoryReader in llama_index, you need to import it from the llama_index library. Once imported, you can create an instance of the SimpleDirectoryReader class by providing the directory path as an argument. Then, you can use the `load_data()` method on the SimpleDirectoryReader instance to load the documents from the specified directory.</b>