agent2/app.py

# Displaying final output format
# from IPython.display import display, Markdown, Latex
# LangChain Dependencies
from langchain.prompts import PromptTemplate
from langchain_core.output_parsers import JsonOutputParser, StrOutputParser
from langchain_community.chat_models import ChatOllama
from langchain_community.tools import DuckDuckGoSearchRun
from langchain_community.utilities import DuckDuckGoSearchAPIWrapper
from langgraph.graph import END, StateGraph
# For State Graph 
from typing_extensions import TypedDict
import os

# Defining LLM
local_llm = 'llama3.2'
llama3 = ChatOllama(model=local_llm, temperature=0)
llama3_json = ChatOllama(model=local_llm, format='json', temperature=0)

# Web Search Tool

wrapper = DuckDuckGoSearchAPIWrapper(max_results=25)
web_search_tool = DuckDuckGoSearchRun(api_wrapper=wrapper)

# Generation Prompt

generate_prompt = PromptTemplate(
    template="""
    
    <|begin_of_text|>
    
    <|start_header_id|>system<|end_header_id|> 
    
    You are an AI assistant for Research Question Tasks, that synthesizes web search results. 
    Strictly use the following pieces of web search context to answer the question. If you don't know the answer, just say that you don't know. 
    keep the answer concise, but provide all of the details you can in the form of a research report. 
    Only make direct references to material if provided in the context.
    
    <|eot_id|>
    
    <|start_header_id|>user<|end_header_id|>
    
    Question: {question} 
    Web Search Context: {context} 
    Answer: 
    
    <|eot_id|>
    
    <|start_header_id|>assistant<|end_header_id|>""",
    input_variables=["question", "context"],
)

# Chain
generate_chain = generate_prompt | llama3 | StrOutputParser()

# Test Run
# question = "who is Yan Lecun?"
# context = ""
# generation = generate_chain.invoke({"context": context, "question": question})
# print(generation)

# Router

router_prompt = PromptTemplate(
    template="""
    
    <|begin_of_text|>
    
    <|start_header_id|>system<|end_header_id|>
    
    You are an expert at routing a user question to either the generation stage or web search. 
    Use the web search for questions that require more context for a better answer, or recent events.
    Otherwise, you can skip and go straight to the generation phase to respond.
    You do not need to be stringent with the keywords in the question related to these topics.
    Give a binary choice 'web_search' or 'generate' based on the question. 
    Return the JSON with a single key 'choice' with no premable or explanation. 
    
    Question to route: {question} 
    
    <|eot_id|>
    
    <|start_header_id|>assistant<|end_header_id|>
    
    """,
    input_variables=["question"],
)

# Chain
question_router = router_prompt | llama3_json | JsonOutputParser()

# Test Run
# question = "What's up?"
# print(question_router.invoke({"question": question}))

# Query Transformation

query_prompt = PromptTemplate(
    template="""
    
    <|begin_of_text|>
    
    <|start_header_id|>system<|end_header_id|> 
    
    You are an expert at crafting web search queries for research questions.
    More often than not, a user will ask a basic question that they wish to learn more about, however it might not be in the best format. 
    Reword their query to be the most effective web search string possible.
    Return the JSON with a single key 'query' with no premable or explanation. 
    
    Question to transform: {question} 
    
    <|eot_id|>
    
    <|start_header_id|>assistant<|end_header_id|>
    
    """,
    input_variables=["question"],
)

# Chain
query_chain = query_prompt | llama3_json | JsonOutputParser()

# Test Run
# question = "What's happened recently with Gaza?"
# print(query_chain.invoke({"question": question}))


# Graph State
class GraphState(TypedDict):
    """
    Represents the state of our graph.

    Attributes:
        question: question
        generation: LLM generation
        search_query: revised question for web search
        context: web_search result
    """
    question : str
    generation : str
    search_query : str
    context : str

# Node - Generate

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("Step: Generating Final Response")
    question = state["question"]
    context = state["context"]
    print(context)
    # TODO:: 根据context特定的内容生产答案
    # Answer Generation
    generation = generate_chain.invoke({"context": context, "question": question})
    return {"generation": generation}

# Node - Query Transformation

def transform_query(state):
    """
    Transform user question to web search

    Args:
        state (dict): The current graph state

    Returns:
        state (dict): Appended search query
    """
    
    print("Step: Optimizing Query for Web Search")
    question = state['question']
    gen_query = query_chain.invoke({"question": question})
    search_query = gen_query["query"]
    return {"search_query": search_query}


# Node - Web Search

def web_search(state):
    """
    Web search based on the question

    Args:
        state (dict): The current graph state

    Returns:
        state (dict): Appended web results to context
    """

    # search_query = state['search_query']
    # print(f'Step: Searching the Web for: "{search_query}"')
    
    # # Web search tool call
    # search_result = web_search_tool.invoke(search_query)
    print("Step: Web Search")
    search_result = "Web Search Results"
    return {"context": search_result}


# Conditional Edge, Routing

def route_question(state):
    """
    route question to web search or generation.

    Args:
        state (dict): The current graph state

    Returns:
        str: Next node to call
    """

    print("Step: Routing Query")
    question = state['question']
    output = question_router.invoke({"question": question})
    if output['choice'] == "web_search":
        print("Step: Routing Query to Web Search")
        return "websearch"
    elif output['choice'] == 'generate':
        print("Step: Routing Query to Generation")
        return "generate"

# Build the nodes
workflow = StateGraph(GraphState)
workflow.add_node("websearch", web_search)
workflow.add_node("transform_query", transform_query)
workflow.add_node("generate", generate)

# Build the edges
workflow.set_conditional_entry_point(
    route_question,
    {
        "websearch": "transform_query",
        "generate": "generate",
    },
)
workflow.add_edge("transform_query", "websearch")
workflow.add_edge("websearch", "generate")
workflow.add_edge("generate", END)

# Compile the workflow
local_agent = workflow.compile()

def run_agent(query):
    output = local_agent.invoke({"question": query})
    print("=======")
    print(output["generation"])
    # display(Markdown(output["generation"]))

run_agent("What is Latest news About Open AI?")