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from __future__ import annotations
import pickle
from pathlib import Path
from typing import Any, Dict, Iterable, List, Optional
from langchain_core.documents import Document
from langchain_core.retrievers import BaseRetriever
from langchain.callbacks.manager import CallbackManagerForRetrieverRun
class TFIDFRetriever(BaseRetriever):
"""`TF-IDF` retriever.
Largely based on
https://github.com/asvskartheek/Text-Retrieval/blob/master/TF-IDF%20Search%20Engine%20(SKLEARN).ipynb
"""
vectorizer: Any
"""TF-IDF vectorizer."""
docs: List[Document]
"""Documents."""
tfidf_array: Any
"""TF-IDF array."""
k: int = 4
"""Number of documents to return."""
class Config:
"""Configuration for this pydantic object."""
arbitrary_types_allowed = True
@classmethod
def from_texts(
cls,
texts: Iterable[str],
metadatas: Optional[Iterable[dict]] = None,
tfidf_params: Optional[Dict[str, Any]] = None,
**kwargs: Any,
) -> TFIDFRetriever:
try:
from sklearn.feature_extraction.text import TfidfVectorizer
except ImportError:
raise ImportError(
"Could not import scikit-learn, please install with `pip install "
"scikit-learn`."
)
tfidf_params = tfidf_params or {}
vectorizer = TfidfVectorizer(**tfidf_params)
tfidf_array = vectorizer.fit_transform(texts)
metadatas = metadatas or ({} for _ in texts)
docs = [Document(page_content=t, metadata=m) for t, m in zip(texts, metadatas)]
return cls(vectorizer=vectorizer, docs=docs, tfidf_array=tfidf_array, **kwargs)
@classmethod
def from_documents(
cls,
documents: Iterable[Document],
*,
tfidf_params: Optional[Dict[str, Any]] = None,
**kwargs: Any,
) -> TFIDFRetriever:
texts, metadatas = zip(*((d.page_content, d.metadata) for d in documents))
return cls.from_texts(
texts=texts, tfidf_params=tfidf_params, metadatas=metadatas, **kwargs
)
def _get_relevant_documents(
self, query: str, *, run_manager: CallbackManagerForRetrieverRun
) -> List[Document]:
from sklearn.metrics.pairwise import cosine_similarity
query_vec = self.vectorizer.transform(
[query]
) # Ip -- (n_docs,x), Op -- (n_docs,n_Feats)
results = cosine_similarity(self.tfidf_array, query_vec).reshape(
(-1,)
) # Op -- (n_docs,1) -- Cosine Sim with each doc
return_docs = [self.docs[i] for i in results.argsort()[-self.k :][::-1]]
return return_docs
def save_local(
self,
folder_path: str,
file_name: str = "tfidf_vectorizer",
) -> None:
try:
import joblib
except ImportError:
raise ImportError(
"Could not import joblib, please install with `pip install joblib`."
)
path = Path(folder_path)
path.mkdir(exist_ok=True, parents=True)
# Save vectorizer with joblib dump.
joblib.dump(self.vectorizer, path / f"{file_name}.joblib")
# Save docs and tfidf array as pickle.
with open(path / f"{file_name}.pkl", "wb") as f:
pickle.dump((self.docs, self.tfidf_array), f)
@classmethod
def load_local(
cls,
folder_path: str,
file_name: str = "tfidf_vectorizer",
) -> TFIDFRetriever:
try:
import joblib
except ImportError:
raise ImportError(
"Could not import joblib, please install with `pip install joblib`."
)
path = Path(folder_path)
# Load vectorizer with joblib load.
vectorizer = joblib.load(path / f"{file_name}.joblib")
# Load docs and tfidf array as pickle.
with open(path / f"{file_name}.pkl", "rb") as f:
docs, tfidf_array = pickle.load(f)
return cls(vectorizer=vectorizer, docs=docs, tfidf_array=tfidf_array)
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