重新排名者

在本笔记本中，我们将展示如何使用 RedisVL 对搜索结果进行重新排序 （documents 或 chunks or records）。今天的 RedisVL 通过以下方式支持重新排名：

在运行此笔记本之前，请务必：

  1. 已安装redisvl并为此笔记本激活该环境。
  2. 有一个正在运行的 Redis 堆栈实例，并且 RediSearch > 2.4 处于活动状态。

例如，您可以使用 Docker 在本地运行 Redis Stack：

docker run -d -p 6379:6379 -p 8001:8001 redis/redis-stack:latest

This will run Redis on port 6379 and RedisInsight at http://localhost:8001.

# import necessary modules
import os

Simple Reranking

Reranking provides a relevance boost to search results generated by traditional (lexical) or semantic search strategies.

As a simple demonstration, take the passages and user query below:

query = "What is the capital of the United States?"
docs = [
    "Carson City is the capital city of the American state of Nevada. At the 2010 United States Census, Carson City had a population of 55,274.",
    "The Commonwealth of the Northern Mariana Islands is a group of islands in the Pacific Ocean that are a political division controlled by the United States. Its capital is Saipan.",
    "Charlotte Amalie is the capital and largest city of the United States Virgin Islands. It has about 20,000 people. The city is on the island of Saint Thomas.",
    "Washington, D.C. (also known as simply Washington or D.C., and officially as the District of Columbia) is the capital of the United States. It is a federal district. The President of the USA and many major national government offices are in the territory. This makes it the political center of the United States of America.",
    "Capital punishment (the death penalty) has existed in the United States since before the United States was a country. As of 2017, capital punishment is legal in 30 of the 50 states. The federal government (including the United States military) also uses capital punishment."
]

The goal of reranking is to provide a more fine-grained quality improvement to initial search results. With RedisVL, this would likely be results coming back from a search operation like full text or vector.

Using the Cross-Encoder Reranker

To use the cross-encoder reranker we initialize an instance of HFCrossEncoderReranker passing a suitable model (if no model is provided, the cross-encoder/ms-marco-MiniLM-L-6-v2 model is used):

from redisvl.utils.rerank import HFCrossEncoderReranker

cross_encoder_reranker = HFCrossEncoderReranker("BAAI/bge-reranker-base")

Rerank documents with HFCrossEncoderReranker

With the obtained reranker instance we can rerank and truncate the list of documents based on relevance to the initial query.

results, scores = cross_encoder_reranker.rank(query=query, docs=docs)

for result, score in zip(results, scores):
    print(score, " -- ", result)

0.07461125403642654  --  {'content': 'Washington, D.C. (also known as simply Washington or D.C., and officially as the District of Columbia) is the capital of the United States. It is a federal district. The President of the USA and many major national government offices are in the territory. This makes it the political center of the United States of America.'}
0.05220315232872963  --  {'content': 'Charlotte Amalie is the capital and largest city of the United States Virgin Islands. It has about 20,000 people. The city is on the island of Saint Thomas.'}
0.3802368640899658  --  {'content': 'Carson City is the capital city of the American state of Nevada. At the 2010 United States Census, Carson City had a population of 55,274.'}

Using the Cohere Reranker

To initialize the Cohere reranker you'll need to install the cohere library and provide the right Cohere API Key.

#!pip install cohere

import getpass

# setup the API Key
api_key = os.environ.get("COHERE_API_KEY") or getpass.getpass("Enter your Cohere API key: ")

from redisvl.utils.rerank import CohereReranker

cohere_reranker = CohereReranker(limit=3, api_config={"api_key": api_key})

Rerank documents with CohereReranker

Below we will use the CohereReranker to rerank and truncate the list of documents above based on relevance to the initial query.

results, scores = cohere_reranker.rank(query=query, docs=docs)

for result, score in zip(results, scores):
    print(score, " -- ", result)

0.9990564  --  Washington, D.C. (also known as simply Washington or D.C., and officially as the District of Columbia) is the capital of the United States. It is a federal district. The President of the USA and many major national government offices are in the territory. This makes it the political center of the United States of America.
0.7516481  --  Capital punishment (the death penalty) has existed in the United States since before the United States was a country. As of 2017, capital punishment is legal in 30 of the 50 states. The federal government (including the United States military) also uses capital punishment.
0.08882029  --  The Commonwealth of the Northern Mariana Islands is a group of islands in the Pacific Ocean that are a political division controlled by the United States. Its capital is Saipan.

Working with semi-structured documents

Often times the initial result set includes other metadata and components that could be used to steer the reranking relevancy. To accomplish this, we can set the rank_by argument and provide documents with those additional fields.

docs = [
    {
        "source": "wiki",
        "passage": "Carson City is the capital city of the American state of Nevada. At the 2010 United States Census, Carson City had a population of 55,274."
    },
    {
        "source": "encyclopedia",
        "passage": "The Commonwealth of the Northern Mariana Islands is a group of islands in the Pacific Ocean that are a political division controlled by the United States. Its capital is Saipan."
    },
    {
        "source": "textbook",
        "passage": "Charlotte Amalie is the capital and largest city of the United States Virgin Islands. It has about 20,000 people. The city is on the island of Saint Thomas."
    },
    {
        "source": "textbook",
        "passage": "Washington, D.C. (also known as simply Washington or D.C., and officially as the District of Columbia) is the capital of the United States. It is a federal district. The President of the USA and many major national government offices are in the territory. This makes it the political center of the United States of America."
    },
    {
        "source": "wiki",
        "passage": "Capital punishment (the death penalty) has existed in the United States since before the United States was a country. As of 2017, capital punishment is legal in 30 of the 50 states. The federal government (including the United States military) also uses capital punishment."
    }
]

results, scores = cohere_reranker.rank(query=query, docs=docs, rank_by=["passage", "source"])

for result, score in zip(results, scores):
    print(score, " -- ", result)

0.9988121  --  {'source': 'textbook', 'passage': 'Washington, D.C. (also known as simply Washington or D.C., and officially as the District of Columbia) is the capital of the United States. It is a federal district. The President of the USA and many major national government offices are in the territory. This makes it the political center of the United States of America.'}
0.5974905  --  {'source': 'wiki', 'passage': 'Capital punishment (the death penalty) has existed in the United States since before the United States was a country. As of 2017, capital punishment is legal in 30 of the 50 states. The federal government (including the United States military) also uses capital punishment.'}
0.059101548  --  {'source': 'encyclopedia', 'passage': 'The Commonwealth of the Northern Mariana Islands is a group of islands in the Pacific Ocean that are a political division controlled by the United States. Its capital is Saipan.'}

Using the VoyageAI Reranker

To initialize the VoyageAI reranker you'll need to install the voyaeai library and provide the right VoyageAI API Key.

#!pip install voyageai

import getpass

# setup the API Key
api_key = os.environ.get("VOYAGE_API_KEY") or getpass.getpass("Enter your VoyageAI API key: ")

from redisvl.utils.rerank import VoyageAIReranker

reranker = VoyageAIReranker(model="rerank-lite-1", limit=3, api_config={"api_key": api_key})# Please check the available models at https://docs.voyageai.com/docs/reranker

Rerank documents with VoyageAIReranker

Below we will use the VoyageAIReranker to rerank and also truncate the list of documents above based on relevance to the initial query.

results, scores = reranker.rank(query=query, docs=docs)

for result, score in zip(results, scores):
    print(score, " -- ", result)

0.796875  --  Washington, D.C. (also known as simply Washington or D.C., and officially as the District of Columbia) is the capital of the United States. It is a federal district. The President of the USA and many major national government offices are in the territory. This makes it the political center of the United States of America.
0.578125  --  Charlotte Amalie is the capital and largest city of the United States Virgin Islands. It has about 20,000 people. The city is on the island of Saint Thomas.
0.5625  --  Carson City is the capital city of the American state of Nevada. At the 2010 United States Census, Carson City had a population of 55,274.
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