langchain/docs/modules/chat/examples/agent.ipynb

Agent

This notebook covers how to create a custom agent for a chat model. It will utilize chat specific prompts.

In [3]:

from langchain.agents import ZeroShotAgent, Tool, AgentExecutor
from langchain.chains import LLMChain
from langchain.utilities import SerpAPIWrapper

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search = SerpAPIWrapper()
tools = [
    Tool(
        name = "Search",
        func=search.run,
        description="useful for when you need to answer questions about current events"
    )
]

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prefix = """Answer the following questions as best you can, but speaking as a pirate might speak. You have access to the following tools:"""
suffix = """Begin! Remember to speak as a pirate when giving your final answer. Use lots of "Args"""

prompt = ZeroShotAgent.create_prompt(
    tools, 
    prefix=prefix, 
    suffix=suffix, 
    input_variables=[]
)

In [7]:

from langchain.chat_models import ChatOpenAI
from langchain.prompts.chat import (
    ChatPromptTemplate,
    SystemMessagePromptTemplate,
    AIMessagePromptTemplate,
    HumanMessagePromptTemplate,
)
from langchain.schema import (
    AIMessage,
    HumanMessage,
    SystemMessage
)

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messages = [
    SystemMessagePromptTemplate(prompt=prompt),
    HumanMessagePromptTemplate.from_template("{input}\n\nThis was your previous work "
                f"(but I haven't seen any of it! I only see what "
                "you return as final answer):\n{agent_scratchpad}")
]

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prompt = ChatPromptTemplate.from_messages(messages)

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llm_chain = LLMChain(llm=ChatOpenAI(temperature=0), prompt=prompt)

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tool_names = [tool.name for tool in tools]
agent = ZeroShotAgent(llm_chain=llm_chain, allowed_tools=tool_names)

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

In [13]:

agent_executor.run("How many people live in canada as of 2023?")

Out [13]:

> Entering new AgentExecutor chain...
Arrr, ye be in luck, matey! I'll find ye the answer to yer question.

Thought: I need to search for the current population of Canada.
Action: Search
Action Input: "current population of Canada 2023"

Observation: The current population of Canada is 38,623,091 as of Saturday, March 4, 2023, based on Worldometer elaboration of the latest United Nations data.
Thought:Ahoy, me hearties! I've found the answer to yer question.

Final Answer: As of March 4, 2023, the population of Canada be 38,623,091. Arrr!

> Finished chain.

'As of March 4, 2023, the population of Canada be 38,623,091. Arrr!'

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