"""Module implements an agent that uses OpenAI's APIs function enabled API."""
from typing import Any, List, Optional, Sequence, Tuple, Union
from langchain_community.tools.convert_to_openai import format_tool_to_openai_function
from langchain_core.agents import AgentAction, AgentFinish
from langchain_core.language_models import BaseLanguageModel
from langchain_core.messages import (
BaseMessage,
SystemMessage,
)
from langchain_core.prompts import BasePromptTemplate
from langchain_core.prompts.chat import (
BaseMessagePromptTemplate,
ChatPromptTemplate,
HumanMessagePromptTemplate,
MessagesPlaceholder,
)
from langchain_core.pydantic_v1 import root_validator
from langchain_core.runnables import Runnable, RunnablePassthrough
from langchain_core.tools import BaseTool
from langchain.agents import BaseSingleActionAgent
from langchain.agents.format_scratchpad.openai_functions import (
format_to_openai_function_messages,
)
from langchain.agents.output_parsers.openai_functions import (
OpenAIFunctionsAgentOutputParser,
)
from langchain.callbacks.base import BaseCallbackManager
from langchain.callbacks.manager import Callbacks
[docs]class OpenAIFunctionsAgent(BaseSingleActionAgent):
"""An Agent driven by OpenAIs function powered API.
Args:
llm: This should be an instance of ChatOpenAI, specifically a model
that supports using `functions`.
tools: The tools this agent has access to.
prompt: The prompt for this agent, should support agent_scratchpad as one
of the variables. For an easy way to construct this prompt, use
`OpenAIFunctionsAgent.create_prompt(...)`
"""
llm: BaseLanguageModel
tools: Sequence[BaseTool]
prompt: BasePromptTemplate
@root_validator
def validate_prompt(cls, values: dict) -> dict:
prompt: BasePromptTemplate = values["prompt"]
if "agent_scratchpad" not in prompt.input_variables:
raise ValueError(
"`agent_scratchpad` should be one of the variables in the prompt, "
f"got {prompt.input_variables}"
)
return values
@property
def input_keys(self) -> List[str]:
"""Get input keys. Input refers to user input here."""
return ["input"]
@property
def functions(self) -> List[dict]:
return [dict(format_tool_to_openai_function(t)) for t in self.tools]
[docs] def plan(
self,
intermediate_steps: List[Tuple[AgentAction, str]],
callbacks: Callbacks = None,
with_functions: bool = True,
**kwargs: Any,
) -> Union[AgentAction, AgentFinish]:
"""Given input, decided what to do.
Args:
intermediate_steps: Steps the LLM has taken to date, along with observations
**kwargs: User inputs.
Returns:
Action specifying what tool to use.
"""
agent_scratchpad = format_to_openai_function_messages(intermediate_steps)
selected_inputs = {
k: kwargs[k] for k in self.prompt.input_variables if k != "agent_scratchpad"
}
full_inputs = dict(**selected_inputs, agent_scratchpad=agent_scratchpad)
prompt = self.prompt.format_prompt(**full_inputs)
messages = prompt.to_messages()
if with_functions:
predicted_message = self.llm.predict_messages(
messages,
functions=self.functions,
callbacks=callbacks,
)
else:
predicted_message = self.llm.predict_messages(
messages,
callbacks=callbacks,
)
agent_decision = OpenAIFunctionsAgentOutputParser._parse_ai_message(
predicted_message
)
return agent_decision
[docs] async def aplan(
self,
intermediate_steps: List[Tuple[AgentAction, str]],
callbacks: Callbacks = None,
**kwargs: Any,
) -> Union[AgentAction, AgentFinish]:
"""Given input, decided what to do.
Args:
intermediate_steps: Steps the LLM has taken to date,
along with observations
**kwargs: User inputs.
Returns:
Action specifying what tool to use.
"""
agent_scratchpad = format_to_openai_function_messages(intermediate_steps)
selected_inputs = {
k: kwargs[k] for k in self.prompt.input_variables if k != "agent_scratchpad"
}
full_inputs = dict(**selected_inputs, agent_scratchpad=agent_scratchpad)
prompt = self.prompt.format_prompt(**full_inputs)
messages = prompt.to_messages()
predicted_message = await self.llm.apredict_messages(
messages, functions=self.functions, callbacks=callbacks
)
agent_decision = OpenAIFunctionsAgentOutputParser._parse_ai_message(
predicted_message
)
return agent_decision
[docs] def return_stopped_response(
self,
early_stopping_method: str,
intermediate_steps: List[Tuple[AgentAction, str]],
**kwargs: Any,
) -> AgentFinish:
"""Return response when agent has been stopped due to max iterations."""
if early_stopping_method == "force":
# `force` just returns a constant string
return AgentFinish(
{"output": "Agent stopped due to iteration limit or time limit."}, ""
)
elif early_stopping_method == "generate":
# Generate does one final forward pass
agent_decision = self.plan(
intermediate_steps, with_functions=False, **kwargs
)
if isinstance(agent_decision, AgentFinish):
return agent_decision
else:
raise ValueError(
f"got AgentAction with no functions provided: {agent_decision}"
)
else:
raise ValueError(
"early_stopping_method should be one of `force` or `generate`, "
f"got {early_stopping_method}"
)
[docs] @classmethod
def create_prompt(
cls,
system_message: Optional[SystemMessage] = SystemMessage(
content="You are a helpful AI assistant."
),
extra_prompt_messages: Optional[List[BaseMessagePromptTemplate]] = None,
) -> BasePromptTemplate:
"""Create prompt for this agent.
Args:
system_message: Message to use as the system message that will be the
first in the prompt.
extra_prompt_messages: Prompt messages that will be placed between the
system message and the new human input.
Returns:
A prompt template to pass into this agent.
"""
_prompts = extra_prompt_messages or []
messages: List[Union[BaseMessagePromptTemplate, BaseMessage]]
if system_message:
messages = [system_message]
else:
messages = []
messages.extend(
[
*_prompts,
HumanMessagePromptTemplate.from_template("{input}"),
MessagesPlaceholder(variable_name="agent_scratchpad"),
]
)
return ChatPromptTemplate(messages=messages)
[docs]def create_openai_functions_agent(
llm: BaseLanguageModel, tools: Sequence[BaseTool], prompt: ChatPromptTemplate
) -> Runnable:
"""Create an agent that uses OpenAI function calling.
Examples:
Creating an agent with no memory
.. code-block:: python
from langchain_community.chat_models import ChatOpenAI
from langchain.agents import AgentExecutor, create_openai_functions_agent
from langchain import hub
prompt = hub.pull("hwchase17/openai-functions-agent")
model = ChatOpenAI()
tools = ...
agent = create_openai_functions_agent(model, tools, prompt)
agent_executor = AgentExecutor(agent=agent, tools=tools)
agent_executor.invoke({"input": "hi"})
# Using with chat history
from langchain_core.messages import AIMessage, HumanMessage
agent_executor.invoke(
{
"input": "what's my name?",
"chat_history": [
HumanMessage(content="hi! my name is bob"),
AIMessage(content="Hello Bob! How can I assist you today?"),
],
}
)
Args:
llm: LLM to use as the agent. Should work with OpenAI function calling,
so either be an OpenAI model that supports that or a wrapper of
a different model that adds in equivalent support.
tools: Tools this agent has access to.
prompt: The prompt to use, must have an input key of `agent_scratchpad`.
Returns:
A runnable sequence representing an agent. It takes as input all the same input
variables as the prompt passed in does. It returns as output either an
AgentAction or AgentFinish.
"""
if "agent_scratchpad" not in prompt.input_variables:
raise ValueError(
"Prompt must have input variable `agent_scratchpad`, but wasn't found. "
f"Found {prompt.input_variables} instead."
)
llm_with_tools = llm.bind(
functions=[format_tool_to_openai_function(t) for t in tools]
)
agent = (
RunnablePassthrough.assign(
agent_scratchpad=lambda x: format_to_openai_function_messages(
x["intermediate_steps"]
)
)
| prompt
| llm_with_tools
| OpenAIFunctionsAgentOutputParser()
)
return agent