推論し、行動するChatGPT(OpenAI API) Agentを作る – langchain ReAct Custom Agent基礎 –

# LLM(ChatGPT)に以下の質問を投げる
Question: What is the elevation range for the area that the eastern sector of the Colorado orogeny extends into?
Thought: 

Thought: I need to search Colorado orogeny, find the area that the eastern sector of the Colorado orogeny extends into, then find the elevation range of the area.
Action: Search[Colorado orogeny]

import wikipedia

result = Wikipedia.search("Colorado orogeny")

# The Colorado orogeny was an episode of mountain building (an orogeny) in Colorado and surrounding areas.
return result.summary()

Question: What is the elevation range for the area that the eastern sector of the Colorado orogeny extends into?
Observation: The Colorado orogeny was an episode of mountain building (an orogeny) in Colorado and surrounding areas.
Thought:

Action: Finish[1,800 to 7,000 ft]

EXAMPLES = [
    """質問: What is the elevation range for the area that the eastern sector of the Colorado orogeny extends into?
考察: I need to search Colorado orogeny, find the area that the eastern sector of the Colorado orogeny extends into, then find the elevation range of the area.
行動: Search[Colorado orogeny]
結果: The Colorado orogeny was an episode of mountain building (an orogeny) in Colorado and surrounding areas.
考察: It does not mention the eastern sector. So I need to look up eastern sector.
行動: Lookup[eastern sector]
...

SUFFIX = """\n質問: {input}
{agent_scratchpad}"""

from langchain.prompts.prompt import PromptTemplate

# 基本は上記で作成したReActの構文をFewShotLearningしている
#   最終的に下記の形でJoinしている
#   template = example_separator.join([prefix, *examples, suffix])
WIKI_CUSTOM_PROMPT = PromptTemplate.from_examples(
    EXAMPLES, SUFFIX, ["input", "agent_scratchpad"]
)

class ReActCustomAgent(Agent):
    """Agent for the ReAct chain."""

    output_parser: AgentOutputParser = Field(default_factory=ReActOutputParser)

    # Action句を解析して、SearchなどのActionに移るか、終わらせるかを判断する
    @classmethod
    def _get_default_output_parser(cls, **kwargs: Any) -> AgentOutputParser:
        return ReActOutputParser()

    # FewShotLearning + 質問Promptで使うための文字列を指定
    # 今回は上で作成したものを利用
    @classmethod
    def create_prompt(cls, tools: Sequence[BaseTool]) -> BasePromptTemplate:
        """Return default prompt."""
        return WIKI_CUSTOM_PROMPT

    # Observation[観察]部の接頭辞を指定
    @property
    def observation_prefix(self) -> str:
        """Prefix to append the observation with."""
        return "観察: "

    # (完全には追いきれていないが)推論を止める単語
    @property
    def _stop(self) -> List[str]:
        return ["\n観察:"]

    # thought
    #   thoughts += (f"\n{self.observation_prefix}{observation}\n{self.llm_prefix}")
    @property
    def llm_prefix(self) -> str:
        """Prefix to append the LLM call with."""
        return "考察:"

import re
from typing import Union

from langchain.agents.agent import AgentOutputParser
from langchain.schema import AgentAction, AgentFinish, OutputParserException

# Prompt Exampleに合わせてテキスト処理
# Action句を解析して、SearchなどのActionに移るか、終わらせるかを判断する
class ReActOutputParser(AgentOutputParser):
    def parse(self, text: str) -> Union[AgentAction, AgentFinish]:
        action_prefix = "行動: "
        if not text.strip().split("\n")[-1].startswith(action_prefix):
            raise OutputParserException(f"Could not parse LLM Output: {text}")
        action_block = text.strip().split("\n")[-1]

        action_str = action_block[len(action_prefix) :]
        
        re_matches = re.search(r"(.*?)\[(.*?)\]", action_str)
        if re_matches is None:
            raise OutputParserException(
                f"Could not parse action directive: {action_str}"
            )
        action, action_input = re_matches.group(1), re_matches.group(2)

        # 最後が行動: Finishであれば処理を終わらせる
        if action == "完了":
            return AgentFinish({"output": action_input}, text)
        else:
            return AgentAction(action, action_input, text)

## 動作確認ではada必須で！！！（
llm = OpenAI(temperature=0)

docstore = DocstoreExplorer(Wikipedia())
docstore_explorer = DocstoreExplorer(docstore)

# TemplateのAction内で指定した文字列と、実装した関数をつなぎ合わせる定義
tools = [
    Tool(
        name="Search",
        func=docstore_explorer.search,
        description="Search for a term in the docstore.",
    ),
    Tool(
        name="Lookup",
        func=docstore_explorer.lookup,
        description="Lookup a term in the docstore.",
    ),
]

agent = ReActCustomAgent.from_llm_and_tools(
  llm,
  tools,
)

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

question = "I would like to know the name of one of Darth Vader's son's associates."
agent_executor.run(question)


--------------

> Entering new AgentExecutor chain...
考察: I need to search Darth Vader's son and find one of his associates.
行動: Search[Darth Vader's son]
結果: Darth Vader is a fictional character in the Star Wars franchise. The character is the central antagonist of the original trilogy and, as Anakin Skywalker, is one of the main protagonists in the prequel trilogy. Star Wars creator George Lucas has collectively referred to the first six episodic films of the franchise as "the tragedy of Darth Vader". Darth Vader has become one of the most iconic villains in popular culture, and has been listed among the greatest villains and fictional characters ever. His masked face and helmet, in particular, is one of the most iconic character designs of all time.
Originally a slave on Tatooine, Anakin Skywalker is a Jedi prophesied to bring balance to the Force. He is lured to the dark side of the Force by Chancellor Palpatine (Darth Sidious) and becomes a Sith Lord, assuming the name of Darth Vader. After a lightsaber battle with his former mentor Obi-Wan Kenobi on Mustafar, in which he is severely injured, Vader is transformed into a cyborg. Now the Emperor's handpicked right-hand, he serves the Galactic Empire for over two decades as the Commander-in-Chief of its forces, purging the last Jedi and hunting the Rebels. Vader ultimately redeems himself by saving his son, Luke Skywalker, and killing Palpatine, sacrificing his own life in the process. He is also the secret husband of Padmé Amidala, the biological father of Princess Leia, and the grandfather of Kylo Ren (Ben Solo). In the non-canonical Star Wars Legends continuity, he is also the grandfather of Ben Skywalker, his eponym Anakin Solo, Jaina Solo and Darth Caedus (Jacen Solo), and the great-grandfather of Allana Solo.
The character has been portrayed by numerous actors: David Prowse physically portrayed Vader while James Earl Jones has voiced him in all of the films and some television shows, and Sebastian Shaw portrayed the unmasked Anakin in Return of the Jedi, as well as the character's spirit in the original release of that film. Jake Lloyd played Anakin Skywalker as a child in The Phantom Menace, the first film of the prequel trilogy, while Hayden Christensen played him as a young adult in the following two films, post-2004 releases of Return of the Jedi, and Obi-Wan Kenobi.
In addition to the first six Star Wars films, the character appears in the anthology film Rogue One. He also appears in television series (most substantially The Clone Wars) and numerous iterations of the Star Wars Expanded Universe, including video games, novels, and comic books. Due to Vader's popularity, various merchandise of the character, such as action figures and replicas of his lightsaber, has been produced.
考察: Darth Vader has a son, Luke Skywalker. I need to search Luke Skywalker and find one of his associates.
行動: Search[Luke Skywalker]
結果: Could not find [Luke Skywalker]. Similar: ['Luke Skywalker', 'Skywalker family', 'Darth Vader', 'Rey (Star Wars)', 'Mara Jade', 'Jedi', 'Chapter 16: The Rescue', 'Star Wars: From the Adventures of Luke Skywalker', 'Skellig Michael', 'Kylo Ren']
考察: To find one of Luke Skywalker's associates, I can search Luke Skywalker (Star Wars).
行動: Search[Luke Skywalker (Star Wars)]
結果: Luke Skywalker is a fictional character and the protagonist of the original film trilogy of the Star Wars franchise created by George Lucas. Portrayed by Mark Hamill, Luke first appeared in Star Wars (1977), and he returned in The Empire Strikes Back (1980) and Return of the Jedi (1983). Over three decades later, Hamill returned as Luke in the Star Wars sequel trilogy, cameoing in The Force Awakens (2015) before playing a major role in The Last Jedi (2017) and The Rise of Skywalker (2019). He later played a digitally de-aged version of the character in the Disney+ series The Mandalorian, appearing in the second-season finale, which premiered in 2020, and The Book of Boba Fett, in the sixth episode, released in 2022.
Originally a farmer on Tatooine living with his uncle and aunt, Luke becomes a pivotal figure in the Rebel Alliance's struggle against the Galactic Empire. The son of fallen Jedi Knight Anakin Skywalker (turned Sith Lord Darth Vader) and Padmé Amidala, Luke is the twin brother of Rebellion leader Princess Leia and eventual brother-in-law of the smuggler Han Solo. Luke trains to be a Jedi under Jedi Masters Obi-Wan Kenobi and Yoda and rebuilds the Jedi Order. He later trains his nephew Ben Solo and mentors Rey. Though Luke dies at the end of The Last Jedi, he returns as a Force spirit in The Rise of Skywalker, encouraging Rey to face her grandfather, the resurrected Emperor Palpatine. At the end of the film, the spirits of Luke and Leia give Rey their blessing to adopt the Skywalker surname and continue their family's legacy.
The character also briefly appears in the prequel film Episode III – Revenge of the Sith as an infant, portrayed by Aidan Barton, and in the Disney+ series Obi-Wan Kenobi as a child, portrayed by Grant Feely. In the de-canonized Star Wars Expanded Universe (renamed Legends), Luke is a main character in many stories set after Return of the Jedi, which depict him as a powerful Jedi Master, the husband of Mara Jade, father of Ben Skywalker, and maternal uncle of Jaina, Jacen and Anakin Solo.
考察: Luke Skywalker has many associates, such as Han Solo, Obi-Wan Kenobi, Yoda, Rey, and Ben Solo. So one of Darth Vader's son's associates is Han Solo.
完了: Finish[Han Solo]

> Finished chain.
Han Solo