WebDemoLLM / vectorstore.py
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from typing import Any, List, Optional, Type
from pydantic import BaseModel, Extra, Field
from langchain.base_language import BaseLanguageModel
from langchain.chains.qa_with_sources.retrieval import RetrievalQAWithSourcesChain
from langchain.chains.retrieval_qa.base import RetrievalQA
from langchain.document_loaders.base import BaseLoader
from langchain.embeddings.base import Embeddings
from langchain.embeddings.openai import OpenAIEmbeddings
from langchain.llms.openai import OpenAI
from langchain.schema import Document
from langchain.text_splitter import RecursiveCharacterTextSplitter, TextSplitter
from langchain.vectorstores.base import VectorStore
from langchain.vectorstores.chroma import Chroma
def _get_default_text_splitter() -> TextSplitter:
return RecursiveCharacterTextSplitter(chunk_size=1000, chunk_overlap=0)
class VectorStoreIndexWrapper(BaseModel):
"""Wrapper around a vectorstore for easy access."""
vectorstore: VectorStore
class Config:
"""Configuration for this pydantic object."""
extra = Extra.forbid
arbitrary_types_allowed = True
def query(
self, question: str, llm: Optional[BaseLanguageModel] = None, **kwargs: Any
) -> str:
"""Query the vectorstore."""
llm = llm or OpenAI(temperature=0)
chain = RetrievalQA.from_chain_type(
llm, retriever=self.vectorstore.as_retriever(), **kwargs
)
return chain.run(question)
def query_with_sources(
self, question: str, llm: Optional[BaseLanguageModel] = None, **kwargs: Any
) -> dict:
"""Query the vectorstore and get back sources."""
llm = llm or OpenAI(temperature=0)
chain = RetrievalQAWithSourcesChain.from_chain_type(
llm, retriever=self.vectorstore.as_retriever(), **kwargs
)
return chain({chain.question_key: question})
class VectorstoreIndexCreator(BaseModel):
"""Logic for creating indexes."""
vectorstore_cls: Type[VectorStore] = Chroma
embedding: Embeddings = Field(default_factory=OpenAIEmbeddings)
text_splitter: TextSplitter = Field(default_factory=_get_default_text_splitter)
vectorstore_kwargs: dict = Field(default_factory=dict)
class Config:
"""Configuration for this pydantic object."""
extra = Extra.forbid
arbitrary_types_allowed = True
def from_loaders(self, loaders: List[BaseLoader]) -> VectorStoreIndexWrapper:
"""Create a vectorstore index from loaders."""
docs = []
for loader in loaders:
docs.extend(loader.load())
return self.from_documents(docs)
def from_documents(self, documents: List[Document]) -> VectorStoreIndexWrapper:
"""Create a vectorstore index from documents."""
sub_docs = self.text_splitter.split_documents(documents)
vectorstore = self.vectorstore_cls.from_documents(
sub_docs, self.embedding, **self.vectorstore_kwargs
)
return VectorStoreIndexWrapper(vectorstore=vectorstore)
def from_persistent_index(self, path: str) -> VectorStoreIndexWrapper:
"""Load a vectorstore index from a persistent index."""
vectorstore = self.vectorstore_cls(persist_directory=path, embedding_function=self.embedding)
return VectorStoreIndexWrapper(vectorstore=vectorstore)