大規模言語モデルのためのLangChain入門

python -m venv langchain-env
source langchain-env/bin/activate
pip install langchain

pip install openai

export OPENAI_API_KEY=your_api_key_here

from langchain import PromptTemplate
 
template = """
You are an assistant that helps users write professional emails.
 
Given the following context:
{context}
 
Write a professional email response. Sign the email as "John".
"""
 
prompt = PromptTemplate(
    input_variables=["context"],
    template=template,
)

context = "I need to inform my boss that I'll be taking a vacation next week."
print(prompt.format(context=context))

from langchain.llms import OpenAI
 
llm = OpenAI(model_name="text-davinci-003")
 
result = llm("What is the capital of France?")
print(result)

from langchain.chains import LLMChain
from langchain.prompts import PromptTemplate
 
first_prompt = PromptTemplate(
    input_variables=["product"],
    template="What is a good name for a company that makes {product}?",
)
 
second_prompt = PromptTemplate(
    input_variables=["company_name"],
    template="Write a catchphrase for the following company: {company_name}",
)
 
chain = LLMChain(llm=llm, prompt=first_prompt)
second_chain = LLMChain(llm=llm, prompt=second_prompt)
 
result = chain.run("colorful socks")
print(f"Company name: {result}")
 
result = second_chain.run(result)
print(f"Catchphrase: {result}")

from langchain.agents import initialize_agent, Tool
from langchain.tools import BaseTool
from langchain.llms import OpenAI
 
def search_api(query):
    return "Search results for {query} would be returned here"
 
def calculator(expression):
    return eval(expression)
 
search_tool = Tool(
    name="Search",
    func=search_api,
    description="Useful for searching the internet for information."
)
 
calculator_tool = Tool(
    name="Calculator",
    func=calculator,
    description="Useful for doing math calculations."
)
 
tools = [search_tool, calculator_tool]
 
llm = OpenAI(temperature=0)
agent = initialize_agent(tools, llm, agent="zero-shot-react-description", verbose=True)
 
result = agent.run("What is the population of Canada divided by the population of the United States?")
print(result)