Adaptive RAG¶
Adaptive RAG is a strategy for RAG that unites (1) query analysis with (2) active / self-corrective RAG.
In the paper, they report query analysis to route across:
- No Retrieval
- Single-shot RAG
- Iterative RAG
Let's build on this using LangGraph.
In our implementation, we will route between:
- Web search: for questions related to recent events
- Self-corrective RAG: for questions related to our index
Setup¶
First, let's install our required packages and set our API keys
%%capture --no-stderr
! pip install -U langchain_community tiktoken langchain-openai langchain-cohere langchainhub chromadb langchain langgraph tavily-python
import getpass
import os
def _set_env(var: str):
if not os.environ.get(var):
os.environ[var] = getpass.getpass(f"{var}: ")
_set_env("OPENAI_API_KEY")
_set_env("COHERE_API_KEY")
_set_env("TAVILY_API_KEY")
Set up LangSmith for LangGraph development
Sign up for LangSmith to quickly spot issues and improve the performance of your LangGraph projects. LangSmith lets you use trace data to debug, test, and monitor your LLM apps built with LangGraph — read more about how to get started here.
Create Index¶
### Build Index
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain_community.document_loaders import WebBaseLoader
from langchain_community.vectorstores import Chroma
from langchain_openai import OpenAIEmbeddings
### from langchain_cohere import CohereEmbeddings
# Set embeddings
embd = OpenAIEmbeddings()
# Docs to index
urls = [
"https://lilianweng.github.io/posts/2023-06-23-agent/",
"https://lilianweng.github.io/posts/2023-03-15-prompt-engineering/",
"https://lilianweng.github.io/posts/2023-10-25-adv-attack-llm/",
]
# Load
docs = [WebBaseLoader(url).load() for url in urls]
docs_list = [item for sublist in docs for item in sublist]
# Split
text_splitter = RecursiveCharacterTextSplitter.from_tiktoken_encoder(
chunk_size=500, chunk_overlap=0
)
doc_splits = text_splitter.split_documents(docs_list)
# Add to vectorstore
vectorstore = Chroma.from_documents(
documents=doc_splits,
collection_name="rag-chroma",
embedding=embd,
)
retriever = vectorstore.as_retriever()
LLMs¶
Using Pydantic with LangChain
This notebook uses Pydantic v2 BaseModel, which requires langchain-core >= 0.3. Using langchain-core < 0.3 will result in errors due to mixing of Pydantic v1 and v2 BaseModels.
### Router
from typing import Literal
from langchain_core.prompts import ChatPromptTemplate
from langchain_openai import ChatOpenAI
from pydantic import BaseModel, Field
# Data model
class RouteQuery(BaseModel):
"""Route a user query to the most relevant datasource."""
datasource: Literal["vectorstore", "web_search"] = Field(
...,
description="Given a user question choose to route it to web search or a vectorstore.",
)
# LLM with function call
llm = ChatOpenAI(model="gpt-3.5-turbo-0125", temperature=0)
structured_llm_router = llm.with_structured_output(RouteQuery)
# Prompt
system = """You are an expert at routing a user question to a vectorstore or web search.
The vectorstore contains documents related to agents, prompt engineering, and adversarial attacks.
Use the vectorstore for questions on these topics. Otherwise, use web-search."""
route_prompt = ChatPromptTemplate.from_messages(
[
("system", system),
("human", "{question}"),
]
)
question_router = route_prompt | structured_llm_router
print(
question_router.invoke(
{"question": "Who will the Bears draft first in the NFL draft?"}
)
)
print(question_router.invoke({"question": "What are the types of agent memory?"}))
API Reference:
ChatPromptTemplate | ChatOpenAI
### Retrieval Grader
# Data model
class GradeDocuments(BaseModel):
"""Binary score for relevance check on retrieved documents."""
binary_score: str = Field(
description="Documents are relevant to the question, 'yes' or 'no'"
)
# LLM with function call
llm = ChatOpenAI(model="gpt-3.5-turbo-0125", temperature=0)
structured_llm_grader = llm.with_structured_output(GradeDocuments)
# Prompt
system = """You are a grader assessing relevance of a retrieved document to a user question. \n
If the document contains keyword(s) or semantic meaning related to the user question, grade it as relevant. \n
It does not need to be a stringent test. The goal is to filter out erroneous retrievals. \n
Give a binary score 'yes' or 'no' score to indicate whether the document is relevant to the question."""
grade_prompt = ChatPromptTemplate.from_messages(
[
("system", system),
("human", "Retrieved document: \n\n {document} \n\n User question: {question}"),
]
)
retrieval_grader = grade_prompt | structured_llm_grader
question = "agent memory"
docs = retriever.invoke(question)
doc_txt = docs[1].page_content
print(retrieval_grader.invoke({"question": question, "document": doc_txt}))
### Generate
from langchain import hub
from langchain_core.output_parsers import StrOutputParser
# Prompt
prompt = hub.pull("rlm/rag-prompt")
# LLM
llm = ChatOpenAI(model_name="gpt-3.5-turbo", temperature=0)
# Post-processing
def format_docs(docs):
return "\n\n".join(doc.page_content for doc in docs)
# Chain
rag_chain = prompt | llm | StrOutputParser()
# Run
generation = rag_chain.invoke({"context": docs, "question": question})
print(generation)
The design of generative agents combines LLM with memory, planning, and reflection mechanisms to enable agents to behave based on past experience and interact with other agents. Memory stream is a long-term memory module that records agents' experiences in natural language. The retrieval model surfaces context to inform the agent's behavior based on relevance, recency, and importance.
API Reference:
StrOutputParser
### Hallucination Grader
# Data model
class GradeHallucinations(BaseModel):
"""Binary score for hallucination present in generation answer."""
binary_score: str = Field(
description="Answer is grounded in the facts, 'yes' or 'no'"
)
# LLM with function call
llm = ChatOpenAI(model="gpt-3.5-turbo-0125", temperature=0)
structured_llm_grader = llm.with_structured_output(GradeHallucinations)
# Prompt
system = """You are a grader assessing whether an LLM generation is grounded in / supported by a set of retrieved facts. \n
Give a binary score 'yes' or 'no'. 'Yes' means that the answer is grounded in / supported by the set of facts."""
hallucination_prompt = ChatPromptTemplate.from_messages(
[
("system", system),
("human", "Set of facts: \n\n {documents} \n\n LLM generation: {generation}"),
]
)
hallucination_grader = hallucination_prompt | structured_llm_grader
hallucination_grader.invoke({"documents": docs, "generation": generation})
### Answer Grader
# Data model
class GradeAnswer(BaseModel):
"""Binary score to assess answer addresses question."""
binary_score: str = Field(
description="Answer addresses the question, 'yes' or 'no'"
)
# LLM with function call
llm = ChatOpenAI(model="gpt-3.5-turbo-0125", temperature=0)
structured_llm_grader = llm.with_structured_output(GradeAnswer)
# Prompt
system = """You are a grader assessing whether an answer addresses / resolves a question \n
Give a binary score 'yes' or 'no'. Yes' means that the answer resolves the question."""
answer_prompt = ChatPromptTemplate.from_messages(
[
("system", system),
("human", "User question: \n\n {question} \n\n LLM generation: {generation}"),
]
)
answer_grader = answer_prompt | structured_llm_grader
answer_grader.invoke({"question": question, "generation": generation})
### Question Re-writer
# LLM
llm = ChatOpenAI(model="gpt-3.5-turbo-0125", temperature=0)
# Prompt
system = """You a question re-writer that converts an input question to a better version that is optimized \n
for vectorstore retrieval. Look at the input and try to reason about the underlying semantic intent / meaning."""
re_write_prompt = ChatPromptTemplate.from_messages(
[
("system", system),
(
"human",
"Here is the initial question: \n\n {question} \n Formulate an improved question.",
),
]
)
question_rewriter = re_write_prompt | llm | StrOutputParser()
question_rewriter.invoke({"question": question})
Web Search Tool¶
### Search
from langchain_community.tools.tavily_search import TavilySearchResults
web_search_tool = TavilySearchResults(k=3)
API Reference:
TavilySearchResults
Construct the Graph¶
Capture the flow in as a graph.
Define Graph State¶
from typing import List
from typing_extensions import TypedDict
class GraphState(TypedDict):
"""
Represents the state of our graph.
Attributes:
question: question
generation: LLM generation
documents: list of documents
"""
question: str
generation: str
documents: List[str]
Define Graph Flow¶
from langchain.schema import Document
def retrieve(state):
"""
Retrieve documents
Args:
state (dict): The current graph state
Returns:
state (dict): New key added to state, documents, that contains retrieved documents
"""
print("---RETRIEVE---")
question = state["question"]
# Retrieval
documents = retriever.invoke(question)
return {"documents": documents, "question": question}
def generate(state):
"""
Generate answer
Args:
state (dict): The current graph state
Returns:
state (dict): New key added to state, generation, that contains LLM generation
"""
print("---GENERATE---")
question = state["question"]
documents = state["documents"]
# RAG generation
generation = rag_chain.invoke({"context": documents, "question": question})
return {"documents": documents, "question": question, "generation": generation}
def grade_documents(state):
"""
Determines whether the retrieved documents are relevant to the question.
Args:
state (dict): The current graph state
Returns:
state (dict): Updates documents key with only filtered relevant documents
"""
print("---CHECK DOCUMENT RELEVANCE TO QUESTION---")
question = state["question"]
documents = state["documents"]
# Score each doc
filtered_docs = []
for d in documents:
score = retrieval_grader.invoke(
{"question": question, "document": d.page_content}
)
grade = score.binary_score
if grade == "yes":
print("---GRADE: DOCUMENT RELEVANT---")
filtered_docs.append(d)
else:
print("---GRADE: DOCUMENT NOT RELEVANT---")
continue
return {"documents": filtered_docs, "question": question}
def transform_query(state):
"""
Transform the query to produce a better question.
Args:
state (dict): The current graph state
Returns:
state (dict): Updates question key with a re-phrased question
"""
print("---TRANSFORM QUERY---")
question = state["question"]
documents = state["documents"]
# Re-write question
better_question = question_rewriter.invoke({"question": question})
return {"documents": documents, "question": better_question}
def web_search(state):
"""
Web search based on the re-phrased question.
Args:
state (dict): The current graph state
Returns:
state (dict): Updates documents key with appended web results
"""
print("---WEB SEARCH---")
question = state["question"]
# Web search
docs = web_search_tool.invoke({"query": question})
web_results = "\n".join([d["content"] for d in docs])
web_results = Document(page_content=web_results)
return {"documents": web_results, "question": question}
### Edges ###
def route_question(state):
"""
Route question to web search or RAG.
Args:
state (dict): The current graph state
Returns:
str: Next node to call
"""
print("---ROUTE QUESTION---")
question = state["question"]
source = question_router.invoke({"question": question})
if source.datasource == "web_search":
print("---ROUTE QUESTION TO WEB SEARCH---")
return "web_search"
elif source.datasource == "vectorstore":
print("---ROUTE QUESTION TO RAG---")
return "vectorstore"
def decide_to_generate(state):
"""
Determines whether to generate an answer, or re-generate a question.
Args:
state (dict): The current graph state
Returns:
str: Binary decision for next node to call
"""
print("---ASSESS GRADED DOCUMENTS---")
state["question"]
filtered_documents = state["documents"]
if not filtered_documents:
# All documents have been filtered check_relevance
# We will re-generate a new query
print(
"---DECISION: ALL DOCUMENTS ARE NOT RELEVANT TO QUESTION, TRANSFORM QUERY---"
)
return "transform_query"
else:
# We have relevant documents, so generate answer
print("---DECISION: GENERATE---")
return "generate"
def grade_generation_v_documents_and_question(state):
"""
Determines whether the generation is grounded in the document and answers question.
Args:
state (dict): The current graph state
Returns:
str: Decision for next node to call
"""
print("---CHECK HALLUCINATIONS---")
question = state["question"]
documents = state["documents"]
generation = state["generation"]
score = hallucination_grader.invoke(
{"documents": documents, "generation": generation}
)
grade = score.binary_score
# Check hallucination
if grade == "yes":
print("---DECISION: GENERATION IS GROUNDED IN DOCUMENTS---")
# Check question-answering
print("---GRADE GENERATION vs QUESTION---")
score = answer_grader.invoke({"question": question, "generation": generation})
grade = score.binary_score
if grade == "yes":
print("---DECISION: GENERATION ADDRESSES QUESTION---")
return "useful"
else:
print("---DECISION: GENERATION DOES NOT ADDRESS QUESTION---")
return "not useful"
else:
pprint("---DECISION: GENERATION IS NOT GROUNDED IN DOCUMENTS, RE-TRY---")
return "not supported"
API Reference:
Document
Compile Graph¶
from langgraph.graph import END, StateGraph, START
workflow = StateGraph(GraphState)
# Define the nodes
workflow.add_node("web_search", web_search) # web search
workflow.add_node("retrieve", retrieve) # retrieve
workflow.add_node("grade_documents", grade_documents) # grade documents
workflow.add_node("generate", generate) # generatae
workflow.add_node("transform_query", transform_query) # transform_query
# Build graph
workflow.add_conditional_edges(
START,
route_question,
{
"web_search": "web_search",
"vectorstore": "retrieve",
},
)
workflow.add_edge("web_search", "generate")
workflow.add_edge("retrieve", "grade_documents")
workflow.add_conditional_edges(
"grade_documents",
decide_to_generate,
{
"transform_query": "transform_query",
"generate": "generate",
},
)
workflow.add_edge("transform_query", "retrieve")
workflow.add_conditional_edges(
"generate",
grade_generation_v_documents_and_question,
{
"not supported": "generate",
"useful": END,
"not useful": "transform_query",
},
)
# Compile
app = workflow.compile()
Use Graph¶
from pprint import pprint
# Run
inputs = {
"question": "What player at the Bears expected to draft first in the 2024 NFL draft?"
}
for output in app.stream(inputs):
for key, value in output.items():
# Node
pprint(f"Node '{key}':")
# Optional: print full state at each node
# pprint.pprint(value["keys"], indent=2, width=80, depth=None)
pprint("\n---\n")
# Final generation
pprint(value["generation"])
---ROUTE QUESTION---
---ROUTE QUESTION TO WEB SEARCH---
---WEB SEARCH---
"Node 'web_search':"
'\n---\n'
---GENERATE---
---CHECK HALLUCINATIONS---
---DECISION: GENERATION IS GROUNDED IN DOCUMENTS---
---GRADE GENERATION vs QUESTION---
---DECISION: GENERATION ADDRESSES QUESTION---
"Node 'generate':"
'\n---\n'
('It is expected that the Chicago Bears could have the opportunity to draft '
'the first defensive player in the 2024 NFL draft. The Bears have the first '
'overall pick in the draft, giving them a prime position to select top '
'talent. The top wide receiver Marvin Harrison Jr. from Ohio State is also '
'mentioned as a potential pick for the Cardinals.')
https://smith.langchain.com/public/7e3aa7e5-c51f-45c2-bc66-b34f17ff2263/r
# Run
inputs = {"question": "What are the types of agent memory?"}
for output in app.stream(inputs):
for key, value in output.items():
# Node
pprint(f"Node '{key}':")
# Optional: print full state at each node
# pprint.pprint(value["keys"], indent=2, width=80, depth=None)
pprint("\n---\n")
# Final generation
pprint(value["generation"])
---ROUTE QUESTION---
---ROUTE QUESTION TO RAG---
---RETRIEVE---
"Node 'retrieve':"
'\n---\n'
---CHECK DOCUMENT RELEVANCE TO QUESTION---
---GRADE: DOCUMENT RELEVANT---
---GRADE: DOCUMENT RELEVANT---
---GRADE: DOCUMENT NOT RELEVANT---
---GRADE: DOCUMENT RELEVANT---
---ASSESS GRADED DOCUMENTS---
---DECISION: GENERATE---
"Node 'grade_documents':"
'\n---\n'
---GENERATE---
---CHECK HALLUCINATIONS---
---DECISION: GENERATION IS GROUNDED IN DOCUMENTS---
---GRADE GENERATION vs QUESTION---
---DECISION: GENERATION ADDRESSES QUESTION---
"Node 'generate':"
'\n---\n'
('The types of agent memory include Sensory Memory, Short-Term Memory (STM) or '
'Working Memory, and Long-Term Memory (LTM) with subtypes of Explicit / '
'declarative memory and Implicit / procedural memory. Sensory memory retains '
'sensory information briefly, STM stores information for cognitive tasks, and '
'LTM stores information for a long time with different types of memories.')
https://smith.langchain.com/public/fdf0a180-6d15-4d09-bb92-f84f2105ca51/r