WikipediaRetriever

Setup:

Install the wikipedia dependency:

.. code-block:: bash

pip install -U wikipedia

Instantiate:

.. code-block:: python

from langchain_community.retrievers import WikipediaRetriever

retriever = WikipediaRetriever()

Usage:

.. code-block:: python

docs = retriever.invoke("TOKYO GHOUL")
print(docs[0].page_content[:100])

.. code-block:: none

Tokyo Ghoul (Japanese: 東京喰種（トーキョーグール）, Hepburn: Tōkyō Gūru) is a Japanese dark fantasy

Use within a chain:

.. code-block:: python

from langchain_core.output_parsers import StrOutputParser
from langchain_core.prompts import ChatPromptTemplate
from langchain_core.runnables import RunnablePassthrough
from langchain_openai import ChatOpenAI

prompt = ChatPromptTemplate.from_template(
    """Answer the question based only on the context provided.

Context: {context}

Question: {question}"""
)

llm = ChatOpenAI(model="gpt-3.5-turbo-0125")

def format_docs(docs):
    return "\n\n".join(doc.page_content for doc in docs)

chain = (
    {"context": retriever | format_docs, "question": RunnablePassthrough()}
    | prompt
    | llm
    | StrOutputParser()
)

chain.invoke(
    "Who is the main character in `Tokyo Ghoul` and does he transform into a ghoul?"
)

.. code-block:: none

 'The main character in Tokyo Ghoul is Ken Kaneki, who transforms into a ghoul after receiving an organ transplant from a ghoul named Rize.'