app.py

from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain.document_loaders import UnstructuredFileLoader, DirectoryLoader
from langchain.embeddings.openai import OpenAIEmbeddings
from langchain.vectorstores import Chroma
from langchain.chat_models import ChatOpenAI
from langchain.chains import RetrievalQA
import os

destination_folder = './data/'
txt_dir_loader = DirectoryLoader(destination_folder, 
                                 loader_cls=UnstructuredFileLoader)
data = txt_dir_loader.load()

text_splitter = RecursiveCharacterTextSplitter(chunk_size=1000, 
                                               chunk_overlap=20)
documents = text_splitter.split_documents(data)

embeddings = OpenAIEmbeddings()

persist_directory = "vector_db"
vectordb = Chroma.from_documents(documents=documents, 
                                 embedding=embeddings, 
                                 persist_directory=persist_directory)
vectordb.persist()
vectordb = None
vectordb = Chroma(persist_directory=persist_directory, 
                  embedding_function=embeddings)

llm = ChatOpenAI(temperature=0, model="gpt-3.5-turbo")
doc_retriever = vectordb.as_retriever()
hp_qa = RetrievalQA.from_chain_type(llm=llm, 
                                    chain_type="stuff", 
                                    retriever=doc_retriever)

def answer_question(query):
  return(hp_qa.run(query))

if __name__ == "main":
  import gradio as gr

  gr.Interface(
    answer_question,
    [
      gr.inputs.Textbox(lines=2, label="Query"),
    ],
    gr.outputs.Textbox(label="Response"),
    title="Ask Harry Potter",
    description=""" Ask Harry Potter is a tool that let's you ask a question with
                    the books' text as reference""",
  ).launch()