forked from Archives/langchain
Harrison/tfidf retriever (#2440)
Harrison Chase
1 year ago
committed by
GitHub
parent
a63cfad558
commit
00bc8df640
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{
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"cells": [
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{
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"cell_type": "markdown",
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"id": "ab66dd43",
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"metadata": {},
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"source": [
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"# TF-IDF Retriever\n",
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"\n",
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"This notebook goes over how to use a retriever that under the hood uses TF-IDF using scikit-learn.\n",
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"\n",
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"For more information on the details of TF-IDF see [this blog post](https://medium.com/data-science-bootcamp/tf-idf-basics-of-information-retrieval-48de122b2a4c)."
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]
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},
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{
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"cell_type": "code",
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"execution_count": 1,
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"id": "393ac030",
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"metadata": {},
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"outputs": [],
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"source": [
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"from langchain.retrievers import TFIDFRetriever"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "a801b57c",
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"metadata": {},
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"outputs": [],
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"source": [
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"# !pip install scikit-learn"
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]
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},
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{
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"cell_type": "markdown",
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"id": "aaf80e7f",
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"metadata": {},
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"source": [
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"## Create New Retriever with Texts"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 3,
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"id": "98b1c017",
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"metadata": {},
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"outputs": [],
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"source": [
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"retriever = TFIDFRetriever.from_texts([\"foo\", \"bar\", \"world\", \"hello\", \"foo bar\"])"
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]
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},
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{
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"cell_type": "markdown",
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"id": "08437fa2",
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"metadata": {},
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"source": [
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"## Use Retriever\n",
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"\n",
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"We can now use the retriever!"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 4,
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"id": "c0455218",
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"metadata": {},
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"outputs": [],
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"source": [
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"result = retriever.get_relevant_documents(\"foo\")"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 5,
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"id": "7dfa5c29",
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"metadata": {},
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"outputs": [
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{
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"data": {
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"text/plain": [
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"[Document(page_content='foo', metadata={}),\n",
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" Document(page_content='foo bar', metadata={}),\n",
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" Document(page_content='hello', metadata={}),\n",
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" Document(page_content='world', metadata={})]"
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]
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},
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"execution_count": 5,
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"metadata": {},
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"output_type": "execute_result"
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}
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],
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"source": [
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"result"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "74bd9256",
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"metadata": {},
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"outputs": [],
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"source": []
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "Python 3 (ipykernel)",
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"language": "python",
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"name": "python3"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 3
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.9.1"
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}
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},
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"nbformat": 4,
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"nbformat_minor": 5
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}
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@ -0,0 +1,47 @@
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"""TF-IDF Retriever.
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Largely based on
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https://github.com/asvskartheek/Text-Retrieval/blob/master/TF-IDF%20Search%20Engine%20(SKLEARN).ipynb"""
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from typing import Any, List
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from pydantic import BaseModel
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from langchain.schema import BaseRetriever, Document
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class TFIDFRetriever(BaseRetriever, BaseModel):
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vectorizer: Any
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docs: List[Document]
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tfidf_array: Any
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k: int = 4
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class Config:
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"""Configuration for this pydantic object."""
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arbitrary_types_allowed = True
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@classmethod
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def from_texts(cls, texts: List[str], **kwargs: Any) -> "TFIDFRetriever":
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from sklearn.feature_extraction.text import TfidfVectorizer
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vectorizer = TfidfVectorizer()
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tfidf_array = vectorizer.fit_transform(texts)
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docs = [Document(page_content=t) for t in texts]
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return cls(vectorizer=vectorizer, docs=docs, tfidf_array=tfidf_array, **kwargs)
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def get_relevant_documents(self, query: str) -> List[Document]:
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from sklearn.metrics.pairwise import cosine_similarity
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query_vec = self.vectorizer.transform(
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[query]
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) # Ip -- (n_docs,x), Op -- (n_docs,n_Feats)
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results = cosine_similarity(self.tfidf_array, query_vec).reshape(
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(-1,)
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) # Op -- (n_docs,1) -- Cosine Sim with each doc
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return_docs = []
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for i in results.argsort()[-self.k :][::-1]:
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return_docs.append(self.docs[i])
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return return_docs
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async def aget_relevant_documents(self, query: str) -> List[Document]:
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raise NotImplementedError
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