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96 lines
3.2 KiB
Python
96 lines
3.2 KiB
Python
"""Chain that does self ask with search."""
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from typing import Any, Optional, Sequence, Tuple, Union
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from langchain.agents.agent import Agent, AgentExecutor
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from langchain.agents.self_ask_with_search.prompt import PROMPT
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from langchain.agents.tools import Tool
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from langchain.llms.base import BaseLLM
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from langchain.prompts.base import BasePromptTemplate
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from langchain.tools.base import BaseTool
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from langchain.utilities.google_serper import GoogleSerperAPIWrapper
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from langchain.utilities.serpapi import SerpAPIWrapper
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class SelfAskWithSearchAgent(Agent):
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"""Agent for the self-ask-with-search paper."""
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@property
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def _agent_type(self) -> str:
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"""Return Identifier of agent type."""
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return "self-ask-with-search"
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@classmethod
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def create_prompt(cls, tools: Sequence[BaseTool]) -> BasePromptTemplate:
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"""Prompt does not depend on tools."""
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return PROMPT
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@classmethod
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def _validate_tools(cls, tools: Sequence[BaseTool]) -> None:
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if len(tools) != 1:
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raise ValueError(f"Exactly one tool must be specified, but got {tools}")
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tool_names = {tool.name for tool in tools}
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if tool_names != {"Intermediate Answer"}:
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raise ValueError(
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f"Tool name should be Intermediate Answer, got {tool_names}"
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)
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def _extract_tool_and_input(self, text: str) -> Optional[Tuple[str, str]]:
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followup = "Follow up:"
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last_line = text.split("\n")[-1]
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if followup not in last_line:
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finish_string = "So the final answer is: "
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if finish_string not in last_line:
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return None
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return "Final Answer", last_line[len(finish_string) :]
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after_colon = text.split(":")[-1]
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if " " == after_colon[0]:
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after_colon = after_colon[1:]
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return "Intermediate Answer", after_colon
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def _fix_text(self, text: str) -> str:
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return f"{text}\nSo the final answer is:"
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@property
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def observation_prefix(self) -> str:
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"""Prefix to append the observation with."""
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return "Intermediate answer: "
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@property
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def llm_prefix(self) -> str:
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"""Prefix to append the LLM call with."""
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return ""
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@property
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def starter_string(self) -> str:
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"""Put this string after user input but before first LLM call."""
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return "Are follow up questions needed here:"
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class SelfAskWithSearchChain(AgentExecutor):
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"""Chain that does self ask with search.
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Example:
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.. code-block:: python
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from langchain import SelfAskWithSearchChain, OpenAI, GoogleSerperAPIWrapper
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search_chain = GoogleSerperAPIWrapper()
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self_ask = SelfAskWithSearchChain(llm=OpenAI(), search_chain=search_chain)
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"""
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def __init__(
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self,
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llm: BaseLLM,
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search_chain: Union[GoogleSerperAPIWrapper, SerpAPIWrapper],
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**kwargs: Any,
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):
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"""Initialize with just an LLM and a search chain."""
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search_tool = Tool(
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name="Intermediate Answer", func=search_chain.run, description="Search"
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)
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agent = SelfAskWithSearchAgent.from_llm_and_tools(llm, [search_tool])
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super().__init__(agent=agent, tools=[search_tool], **kwargs)
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