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Building an LLM-based Reranker for your RAG pipeline

Are you struggling with irrelevant search results in your Retrieval-Augmented Generation (RAG) pipeline?

Imagine having a powerful tool that can intelligently reassess and reorder your search results, significantly improving their relevance to user queries.

In this blog post, we'll show you how to create an LLM-based reranker using Instructor and Pydantic. This approach will:

  • Enhance the accuracy of your search results
  • Leverage the power of large language models (LLMs)
  • Utilize structured outputs for precise information retrieval

By the end of this tutorial, you'll be able to implement a llm reranker to label your synthetic data for fine-tuning a traditional reranker, or to build out an evaluation pipeline for your RAG system. Let's dive in!

Building a Pairwise LLM Judge with Instructor and Pydantic

In this blog post, we'll explore how to create a pairwise LLM judge using Instructor and Pydantic. This judge will evaluate the relevance between a question and a piece of text, demonstrating a practical application of structured outputs in language model interactions.

Introduction

Evaluating text relevance is a common task in natural language processing and information retrieval. By leveraging large language models (LLMs) and structured outputs, we can create a system that judges the similarity or relevance between a question and a given text.

Ensuring Consistent Timestamp Formats with Language Models

Gemini can Understand timestamps in language model outputs, but they can be inconsistent. Video content timestamps vary between HH:MM:SS and MM:SS formats, causing parsing errors and calculations. This post presents a technique to handle timestamps for clips and films without formatting issues.

We combine Pydantic's data validation with custom parsing for consistent timestamp handling. You'll learn to process timestamps in any format, reducing errors in video content workflows. Kinda like how we ensured matching language in multilingal summarization by adding a simple field.

The post provides a solution using Pydantic to improve timestamp handling in language model projects. This method addresses format inconsistencies and enables timestamp processing.

Matching Language in Multilingual Summarization Tasks

When asking language models to summarize text, there's a risk that the generated summary ends up in English, even if the source text is in another language. This is likely due to the instructions being provided in English, biasing the model towards English output.

In this post, we explore techniques to ensure the language of the generated summary matches the language of the source text. We leverage Pydantic for data validation and the langdetect library for language identification.

Simple Synthetic Data Generation

What that people have been using instructor for is to generate synthetic data rather than extracting data itself. We can even use the J-Schemo extra fields to give specific examples to control how we generate data.

Consider the example below. We'll likely generate very simple names.

from typing import Iterable
from pydantic import BaseModel
import instructor
from openai import OpenAI


# Define the UserDetail model
class UserDetail(BaseModel):
    name: str
    age: int


# Patch the OpenAI client to enable the response_model functionality
client = instructor.from_openai(OpenAI())


def generate_fake_users(count: int) -> Iterable[UserDetail]:
    return client.chat.completions.create(
        model="gpt-3.5-turbo",
        response_model=Iterable[UserDetail],
        messages=[
            {"role": "user", "content": f"Generate a {count} synthetic users"},
        ],
    )


for user in generate_fake_users(5):
    print(user)
    #> name='Alice' age=25
    #> name='Bob' age=30
    #> name='Charlie' age=35
    #> name='David' age=40
    #> name='Eve' age=22

Leveraging Simple Examples

We might want to set examples as part of the prompt by leveraging Pydantics configuration. We can set examples directly in the JSON scheme itself.

from typing import Iterable
from pydantic import BaseModel, Field
import instructor
from openai import OpenAI


# Define the UserDetail model
class UserDetail(BaseModel):
    name: str = Field(examples=["Timothee Chalamet", "Zendaya"])
    age: int


# Patch the OpenAI client to enable the response_model functionality
client = instructor.from_openai(OpenAI())


def generate_fake_users(count: int) -> Iterable[UserDetail]:
    return client.chat.completions.create(
        model="gpt-3.5-turbo",
        response_model=Iterable[UserDetail],
        messages=[
            {"role": "user", "content": f"Generate a {count} synthetic users"},
        ],
    )


for user in generate_fake_users(5):
    print(user)
    #> name='John Doe' age=25
    #> name='Jane Smith' age=30
    #> name='Michael Johnson' age=22
    #> name='Emily Davis' age=28
    #> name='David Brown' age=35

By incorporating names of celebrities as examples, we have shifted towards generating synthetic data featuring well-known personalities, moving away from the simplistic, single-word names previously used.

Leveraging Complex Example

To effectively generate synthetic examples with more nuance, lets upgrade to the "gpt-4-turbo-preview" model, use model level examples rather than attribute level examples:

import instructor

from typing import Iterable
from pydantic import BaseModel, ConfigDict
from openai import OpenAI


# Define the UserDetail model
class UserDetail(BaseModel):
    """Old Wizards"""

    name: str
    age: int

    model_config = ConfigDict(
        json_schema_extra={
            "examples": [
                {"name": "Gandalf the Grey", "age": 1000},
                {"name": "Albus Dumbledore", "age": 150},
            ]
        }
    )


# Patch the OpenAI client to enable the response_model functionality
client = instructor.from_openai(OpenAI())


def generate_fake_users(count: int) -> Iterable[UserDetail]:
    return client.chat.completions.create(
        model="gpt-4-turbo-preview",
        response_model=Iterable[UserDetail],
        messages=[
            {"role": "user", "content": f"Generate `{count}` synthetic examples"},
        ],
    )


for user in generate_fake_users(5):
    print(user)
    #> name='Merlin' age=1000
    #> name='Saruman the White' age=700
    #> name='Radagast the Brown' age=600
    #> name='Elminster Aumar' age=1200
    #> name='Mordenkainen' age=850

Leveraging Descriptions

By adjusting the descriptions within our Pydantic models, we can subtly influence the nature of the synthetic data generated. This method allows for a more nuanced control over the output, ensuring that the generated data aligns more closely with our expectations or requirements.

For instance, specifying "Fancy French sounding names" as a description for the name field in our UserDetail model directs the generation process to produce names that fit this particular criterion, resulting in a dataset that is both diverse and tailored to specific linguistic characteristics.

import instructor

from typing import Iterable
from pydantic import BaseModel, Field
from openai import OpenAI


# Define the UserDetail model
class UserDetail(BaseModel):
    name: str = Field(description="Fancy French sounding names")
    age: int


# Patch the OpenAI client to enable the response_model functionality
client = instructor.from_openai(OpenAI())


def generate_fake_users(count: int) -> Iterable[UserDetail]:
    return client.chat.completions.create(
        model="gpt-3.5-turbo",
        response_model=Iterable[UserDetail],
        messages=[
            {"role": "user", "content": f"Generate `{count}` synthetic users"},
        ],
    )


for user in generate_fake_users(5):
    print(user)
    #> name='Jean Luc' age=30
    #> name='Claire Belle' age=25
    #> name='Pierre Leclair' age=40
    #> name='Amelie Rousseau' age=35
    #> name='Etienne Lefevre' age=28

Verifying LLM Citations with Pydantic

Ensuring the accuracy of information is crucial. This blog post explores how Pydantic's powerful and flexible validators can enhance data accuracy through citation verification.

We'll start with using a simple substring check to verify citations. Then we'll use instructor itself to power an LLM to verify citations and align answers with the given citations. Finally, we'll explore how we can use these techniques to generate a dataset of accurate responses.

Good LLM Validation is Just Good Validation

What if your validation logic could learn and adapt like a human, but operate at the speed of software? This is the future of validation and it's already here.

Validation is the backbone of reliable software. But traditional methods are static, rule-based, and can't adapt to new challenges. This post looks at how to bring dynamic, machine learning-driven validation into your software stack using Python libraries like Pydantic and Instructor. We validate these outputs using a validation function which conforms to the structure seen below.

def validation_function(value):
    if condition(value):
        raise ValueError("Value is not valid")
    return mutation(value)