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TF-IDF

TF-IDF means term-frequency times inverse document-frequency.

This notebook goes over how to use a retriever that under the hood uses TF-IDF using scikit-learn package.

For more information on the details of TF-IDF see this blog post.

%pip install --upgrade --quiet  scikit-learn
from langchain_community.retrievers import TFIDFRetriever
API Reference:TFIDFRetriever

Create New Retriever with Textsโ€‹

retriever = TFIDFRetriever.from_texts(["foo", "bar", "world", "hello", "foo bar"])

Create a New Retriever with Documentsโ€‹

You can now create a new retriever with the documents you created.

from langchain_core.documents import Document

retriever = TFIDFRetriever.from_documents(
[
Document(page_content="foo"),
Document(page_content="bar"),
Document(page_content="world"),
Document(page_content="hello"),
Document(page_content="foo bar"),
]
)
API Reference:Document

Use Retrieverโ€‹

We can now use the retriever!

result = retriever.invoke("foo")
result
[Document(page_content='foo', metadata={}),
Document(page_content='foo bar', metadata={}),
Document(page_content='hello', metadata={}),
Document(page_content='world', metadata={})]

Save and loadโ€‹

You can easily save and load this retriever, making it handy for local development!

retriever.save_local("testing.pkl")
retriever_copy = TFIDFRetriever.load_local("testing.pkl")
retriever_copy.invoke("foo")
[Document(page_content='foo', metadata={}),
Document(page_content='foo bar', metadata={}),
Document(page_content='hello', metadata={}),
Document(page_content='world', metadata={})]

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