LangChain and LlamaIndex Projects Lab Book: Hooking Large Language Models Up to the Real World

LangChain and LlamaIndex Projects Lab Book: Hooking Large Language Models Up to the Real World

Mark Watson
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Table of Contents

Preface›

  • Preface
    • Who this book is for
    • What this book covers, and what it deliberately does not
    • What you need to install
    • Where the code lives
    • Requests from the Author
    • About the Author
    • Book Cover
    • Acknowledgements
  • The Stack We’re Building On
    • The whole book, in one dependency list
    • What we are deliberately not installing
    • A note on uv and pyproject.toml
    • The one-time setup
  • Large Language Model Overview
    • Technological Change is Increasing at an Exponential Rate
    • What LLMs Are and What They Are Not
    • Big Tech Businesses vs. Small Startups Using Large Language Models

Part I: LangChain 1.0 and LangGraph 1.0›

  • LangChain 1.0 in One Hour
    • The chapter directory layout
    • Your first chat model call
    • Swapping in a hosted model
    • Two more Runnable methods .stream() and .batch()
    • Prompt templates and the LCEL pipe
    • Output parsers and structured output
    • Tool binding
    • What we covered
  • Swapping Between Local and Commercial Models
    • Switching providers in LangChain
    • Switching providers in LlamaIndex
    • Wrap up
  • RAG Patterns with LangChain
    • A shared corpus loader
    • Pattern 1: naive RAG
    • Pattern 2: retrieve wide, rerank narrow
    • Pattern 3: hybrid dense + sparse retrieval
    • Pattern 4: multi-query rewriting
    • Which pattern for which situation
    • What we covered
  • Running Local LLMs Using Ollama
    • Simple Use of a Local Model Using LangChain
    • Minimal Example Using Ollama for Retrieval Augmented Queries Against Local Documents
    • Wrap Up for Running Local LLMs Using Ollama
  • Extraction of Facts and Relationships from Text Data
    • Key Capabilities of LLMs for Fact and Relationship Extraction
    • Techniques and Approaches
    • Benefits
    • Applications
    • Example Prompts for Getting Information About a Person from Text and Generating JSON
    • From One Record to Many: CSV to JSON
    • What we covered
  • Using LLMs to Summarize Text
    • Example Prompt
    • Code Example
  • LangGraph 1.0 Fundamentals
    • What LangGraph is, and is not
    • Why a graph at all
    • Setup
    • Example 1: hello graph
    • Example 2: state fields with reducers
    • Example 3: conditional routing
    • Example 4: an LLM in a node
    • What we covered
  • Building a ReAct Agent with LangGraph + Ollama
    • The shape of a ReAct loop
    • The tools the agent will use
    • Version 1: create_agent
    • Version 2: the same agent, built explicitly
    • When to reach for which version
    • Watching each step with .stream()
    • Two failure modes worth knowing
    • What we covered
  • Durable, Restart-Safe Agents
    • Three flavors of checkpointer
    • The shared graph
    • Example 1: MemorySaver and thread_id
    • Example 2: SqliteSaver, spread across two processes
    • Example 3: inspecting checkpoint history
    • Two design points worth internalizing
    • What we covered
  • Human-in-the-Loop Patterns
    • Example 1: the minimum viable interrupt
    • Example 2: a tool-approval gate
    • Example 3: pause after a node, edit the checkpoint, resume
    • Two mechanisms, when to reach for each
    • What we covered
  • Multi-Agent Supervisor Pattern
    • The example
    • The specialists
    • The supervisor and the graph
    • Running it
    • Watching the routing
    • When multi-agent is worth it
    • What we covered
  • Natural-Language SQLite
    • The sample database
    • The four SQL tools
    • Building the agent
    • Running it
    • Watching the SQL get written
    • Where to take this next
    • What we covered
  • DBpedia and Wikidata as Agent Tools
    • The example
    • The DBpedia agent
    • The Wikidata agent
    • DBpedia versus Wikidata
    • Where to take this next
    • What we covered
  • A Perplexity-Style Local Search Agent
    • The pipeline
    • The graph
    • Running a complete example
    • Watching each stage
    • Extending this
    • Wrapping up Part I

Part II: LlamaIndex 0.14 and the Workflows API›

  • LlamaIndex
    • What changed since the previous edition
    • The four primitives
    • Setup
    • Your first LlamaIndex program
    • Swapping in a hosted model
    • Persist an index, reload it later
    • Retrievers, without the LLM
    • What we covered
  • Local Documents and Local Embeddings
    • SimpleDirectoryReader deep dive
    • Building Documents by hand
    • Comparing embedding models
    • Chunking with the ingestion pipeline
    • What we covered
  • Choosing an Index Type
    • SummaryIndex: every query touches every Node
    • SimpleKeywordTableIndex: retrieval by exact keyword match
    • QueryFusionRetriever: the practical hybrid pattern
    • Decision tree
    • What we covered
  • RAG with Reranking
    • Baseline: no reranker
    • Same query, with a reranker
    • What the reranker actually costs
    • What we covered
  • The Workflows API
    • The four primitives
    • Setup
    • Hello workflow
    • Chaining steps with a custom event
    • Branching by event type
    • A three-step LLM workflow
    • Workflows vs LangGraph
    • What we covered
  • Building an Agent as a Workflow
    • The Tools
    • Version 1: FunctionAgent
    • Version 2: same agent, built explicitly
    • When to Reach for Which Framework
    • What we covered
  • Multi-Index Query Pipelines
    • RouterQueryEngine: pick one index
    • SubQuestionQueryEngine: decompose and combine
    • When to reach for which
    • What we covered
  • Structured Extraction
    • One-shot extraction
    • Batch extraction
    • When to reach for this vs a chat model with tools
    • What we covered
  • Serving a Workflow with FastAPI
    • The moving parts
    • The workflow being served
    • Terminal 1: the server
    • Terminal 2: the client
    • Scaling from here
    • What we covered
  • Using LLMs To Organize Information in Our Google Drives
    • Setting Up Requirements
    • Write Utility To Fetch All Text Files From Top Level Google Drive Folder
    • Generate Vector Indices for Files in Specific Google Drive Directories
    • Google Drive Example Wrap Up
  • Examples Using Hugging Face Open Source Models
    • Using LangChain as a Wrapper for a Local Hugging Face Pipeline
    • Creating a Custom LlamaIndex Hugging Face LLM Wrapper Class That Runs on Your Laptop
  • Book Wrap Up
    • Where the book falls short
    • Thank you
LangChain and LlamaIndex Projects Lab Book: Hooking Large Language Models Up to the Real World/overview

LangChain and LlamaIndex Projects Lab Book: Hooking Large Language Models Up to the Real World

course_overview

The LangChain and LlamaIndex projects contain excellent documentation and examples. The purpose of this book is to present additional material to learn from.

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Preface3 chapters

Begin part ›
  1. Preface

  2. The Stack We’re Building On

  3. Large Language Model Overview

part_count

Part I: LangChain 1.0 and LangGraph 1.014 chapters

Begin part ›
  1. LangChain 1.0 in One Hour

  2. Swapping Between Local and Commercial Models

  3. RAG Patterns with LangChain

  4. Running Local LLMs Using Ollama

  5. Extraction of Facts and Relationships from Text Data

  6. Using LLMs to Summarize Text

  7. LangGraph 1.0 Fundamentals

  8. Building a ReAct Agent with LangGraph + Ollama

  9. Durable, Restart-Safe Agents

  10. Human-in-the-Loop Patterns

  11. Multi-Agent Supervisor Pattern

  12. Natural-Language SQLite

  13. DBpedia and Wikidata as Agent Tools

  14. A Perplexity-Style Local Search Agent

part_count

Part II: LlamaIndex 0.14 and the Workflows API12 chapters

Begin part ›
  1. LlamaIndex

  2. Local Documents and Local Embeddings

  3. Choosing an Index Type

  4. RAG with Reranking

  5. The Workflows API

  6. Building an Agent as a Workflow

  7. Multi-Index Query Pipelines

  8. Structured Extraction

  9. Serving a Workflow with FastAPI

  10. Using LLMs To Organize Information in Our Google Drives

  11. Examples Using Hugging Face Open Source Models

  12. Book Wrap Up