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from __future__ import annotations
import contextlib
import json
import logging
from typing import Any, Dict, Generator, Iterable, List, Optional, Tuple, Type
import pandas as pd
import sqlalchemy
from langchain.docstore.document import Document
from langchain.schema.embeddings import Embeddings
from langchain.vectorstores.base import VectorStore
from models.article import Article
from models.distance import DistanceStrategy, distance_strategy_limit
from sqlalchemy import delete, text
from sqlalchemy.orm import Session
from utils import str_to_list
DEFAULT_DISTANCE_STRATEGY = DistanceStrategy.COSINE
_LANGCHAIN_DEFAULT_COLLECTION_NAME = "langchain"
def _results_to_docs(docs_and_scores: Any) -> List[Document]:
"""Return docs from docs and scores."""
return [doc for doc, _ in docs_and_scores]
class CustomVectorStore(VectorStore):
"""`Postgres`/`PGVector` vector store.
To use, you should have the ``pgvector`` python package installed.
Args:
connection: Postgres connection string.
embedding_function: Any embedding function implementing
`langchain.embeddings.base.Embeddings` interface.
table_name: The name of the collection to use. (default: langchain)
NOTE: This is not the name of the table, but the name of the collection.
The tables will be created when initializing the store (if not exists)
So, make sure the user has the right permissions to create tables.
distance_strategy: The distance strategy to use. (default: COSINE)
pre_delete_collection: If True, will delete the collection if it exists.
(default: False). Useful for testing.
Example:
.. code-block:: python
from langchain.vectorstores import PGVector
from langchain.embeddings.openai import OpenAIEmbeddings
COLLECTION_NAME = "state_of_the_union_test"
embeddings = OpenAIEmbeddings()
vectorestore = PGVector.from_documents(
embedding=embeddings,
documents=docs,
table_name=COLLECTION_NAME,
connection=connection,
)
"""
def __init__(
self,
connection: sqlalchemy.engine.Connection,
embedding_function: Embeddings,
table_name: str,
column_name: str,
collection_metadata: Optional[dict] = None,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
pre_delete_collection: bool = False,
logger: Optional[logging.Logger] = None,
) -> None:
self._conn = connection
self.embedding_function = embedding_function
self.table_name = table_name
self.column_name = column_name
self.collection_metadata = collection_metadata
self._distance_strategy = distance_strategy
self.pre_delete_collection = pre_delete_collection
self.logger = logger or logging.getLogger(__name__)
self.__post_init__()
def __post_init__(
self,
) -> None:
"""
Initialize the store.
"""
# self._conn = self.connect()
self.EmbeddingStore = Article
@property
def embeddings(self) -> Embeddings:
return self.embedding_function
@contextlib.contextmanager
def _make_session(self) -> Generator[Session, None, None]:
"""Create a context manager for the session, bind to _conn string."""
yield Session(self._conn)
def add_embeddings(
self,
texts: Iterable[str],
embeddings: List[List[float]],
metadatas: Optional[List[dict]] = None,
ids: Optional[List[str]] = None,
**kwargs: Any,
) -> List[str]:
"""Add embeddings to the vectorstore.
Args:
texts: Iterable of strings to add to the vectorstore.
embeddings: List of list of embedding vectors.
metadatas: List of metadatas associated with the texts.
kwargs: vectorstore specific parameters
"""
if not metadatas:
metadatas = [{} for _ in texts]
with Session(self._conn) as session:
for txt, metadata, embedding, id in zip(texts, metadatas, embeddings, ids):
embedding_store = self.EmbeddingStore(
embedding=embedding,
document=txt,
cmetadata=metadata,
custom_id=id,
)
session.add(embedding_store)
session.commit()
return ids
def add_texts(
self,
texts: Iterable[str],
metadatas: Optional[List[dict]] = None,
ids: Optional[List[str]] = None,
**kwargs: Any,
) -> List[str]:
"""Run more texts through the embeddings and add to the vectorstore.
Args:
texts: Iterable of strings to add to the vectorstore.
metadatas: Optional list of metadatas associated with the texts.
kwargs: vectorstore specific parameters
Returns:
List of ids from adding the texts into the vectorstore.
"""
embeddings = self.embedding_function.embed_documents(list(texts))
return self.add_embeddings(
texts=texts, embeddings=embeddings, metadatas=metadatas, ids=ids, **kwargs
)
def similarity_search(
self,
query: str,
k: int = 4,
filter: Optional[dict] = None,
**kwargs: Any,
) -> List[Document]:
"""Run similarity search with PGVector with distance.
Args:
query (str): Query text to search for.
k (int): Number of results to return. Defaults to 4.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List of Documents most similar to the query.
"""
embedding = self.embedding_function.embed_query(text=query)
return self.similarity_search_by_vector(
embedding=embedding,
k=k,
)
def similarity_search_with_score(
self,
query: str,
k: int = 4,
filter: Optional[dict] = None,
) -> List[Tuple[Document, float]]:
"""Return docs most similar to query.
Args:
query: Text to look up documents similar to.
k: Number of Documents to return. Defaults to 4.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List of Documents most similar to the query and score for each.
"""
embedding = self.embedding_function.embed_query(query)
docs = self.similarity_search_with_score_by_vector(embedding=embedding, k=k)
return docs
@property
def distance_strategy(self) -> str | None:
if self._distance_strategy == DistanceStrategy.EUCLIDEAN:
return "<->"
elif self._distance_strategy == DistanceStrategy.COSINE:
return "<=>"
elif self._distance_strategy == DistanceStrategy.MAX_INNER_PRODUCT:
return "<#>"
else:
raise ValueError(
f"Got unexpected value for distance: {self._distance_strategy}. "
f"Should be one of {', '.join([ds.value for ds in DistanceStrategy])}."
)
def similarity_search_with_score_by_vector(
self,
embedding: List[float],
k: int = 4,
) -> List[Tuple[Document, float]]:
results = self.__query_collection(embedding=embedding, k=k)
return self._results_to_docs_and_scores(results)
@staticmethod
def _fetch_title(title: str, abstract: str):
if len(title) > 0:
return title
return abstract.split(".")[0]
def _results_to_docs_and_scores(self, results: Any) -> List[Tuple[Document, float]]:
"""Return docs and scores from results."""
docs = [
(
Document(
page_content=json.dumps(
{
"title": self._fetch_title(
result["title"][0], result["abstract"][0]
),
"authors": result["authors"],
"keywords": result["keywords"],
}
),
metadata={
"id": result["id"],
"doi": result["doi"],
"hal_id": result["hal_id"],
"distance": result["distance"],
"abstract": result["abstract"][0],
},
),
result["distance"] if self.embedding_function is not None else None,
)
for result in results
]
return docs
def __query_collection(
self,
embedding: List[float],
k: int = 4,
) -> List[Any]:
"""Query the collection."""
limit = distance_strategy_limit[self._distance_strategy]
with Session(self._conn) as session:
results = session.execute(
text(
f"""
select
a.id,
a.title_en,
a.doi,
a.hal_id,
a.abstract_en,
string_agg(distinct keyword."name", ', ') as keywords,
string_agg(distinct author."name", ', ') as authors,
abstract_embedding_en {self.distance_strategy} '{str(embedding)}' as distance
from article a
left join article_keyword ON article_keyword.article_id = a.id
left join keyword on article_keyword.keyword_id = keyword.id
left join article_author ON article_author.article_id = a.id
left join author on author.id = article_author.author_id
where
abstract_en != '' and
abstract_en != 'None' and
abstract_embedding_en {self.distance_strategy} '{str(embedding)}' < {limit}
GROUP BY a.id
ORDER BY distance
LIMIT 100;
"""
)
)
results = results.fetchall()
results = pd.DataFrame(
results,
columns=[
"id",
"title",
"doi",
"hal_id",
"abstract",
"keywords",
"authors",
"distance",
],
)
results["abstract"] = results["abstract"].apply(str_to_list)
results["title"] = results["title"].apply(str_to_list)
results = results.to_dict(orient="records")
return results
def similarity_search_by_vector(
self,
embedding: List[float],
k: int = 4,
**kwargs: Any,
) -> List[Document]:
"""Return docs most similar to embedding vector.
Args:
embedding: Embedding to look up documents similar to.
k: Number of Documents to return. Defaults to 4.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List of Documents most similar to the query vector.
"""
docs_and_scores = self.similarity_search_with_score_by_vector(
embedding=embedding, k=k
)
return _results_to_docs(docs_and_scores)
@classmethod
def from_texts(
cls: Type[CustomVectorStore],
texts: List[str],
embedding: Embeddings,
metadatas: Optional[List[dict]] = None,
table_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
ids: Optional[List[str]] = None,
pre_delete_collection: bool = False,
**kwargs: Any,
) -> CustomVectorStore:
"""
Return VectorStore initialized from texts and embeddings.
Postgres connection string is required
"Either pass it as a parameter
or set the PGVECTOR_CONNECTION_STRING environment variable.
"""
embeddings = embedding.embed_documents(list(texts))
return cls.__from(
texts,
embeddings,
embedding,
metadatas=metadatas,
ids=ids,
table_name=table_name,
distance_strategy=distance_strategy,
pre_delete_collection=pre_delete_collection,
**kwargs,
)
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