react-hub.py

from langchain.agents import load_tools
from langchain.llms import OpenAI
from langchain.tools.render import render_text_description
from langchain.agents.output_parsers import ReActSingleInputOutputParser
from langchain.agents.format_scratchpad import format_log_to_str
from langchain import hub
from langchain.agents import AgentExecutor
from config import OPENAI_API_KEY, SERPAPI_API_KEY
import os


os.environ['OPENAI_API_KEY'] = OPENAI_API_KEY
os.environ['SERPAPI_API_KEY'] = SERPAPI_API_KEY

llm = OpenAI(temperature=0)

tools = load_tools(["serpapi", "llm-math"], llm=llm)

prompt = hub.pull("hwchase17/react")
prompt = prompt.partial(
    tools=render_text_description(tools),
    tool_names=", ".join([t.name for t in tools]),
)

llm_with_stop = llm.bind(stop=["\nObservation"])

agent = {
    "input": lambda x: x["input"],
    "agent_scratchpad": lambda x: format_log_to_str(x['intermediate_steps'])
} | prompt | llm_with_stop | ReActSingleInputOutputParser()

agent_executor = AgentExecutor(agent=agent, tools=tools, verbose=True)

agent_executor.invoke({"input": "What is Barack obama's age times two?"})