examples/core-langchain-rag.py

# Importing necessary libraries
import sys
import os
import time

# # Importing RecursiveUrlLoader for web scraping and BeautifulSoup for HTML parsing
# from langchain.document_loaders.recursive_url_loader import RecursiveUrlLoader
# from bs4 import BeautifulSoup as Soup
# import mimetypes

# # List of URLs to scrape
# urls = ["https://langchain-doc.readthedocs.io/en/latest"]

# # Initialize an empty list to store the documents
# docs = []

# # Looping through each URL in the list - this could take some time!
# stf = time.time()  # Start time for performance measurement
# for url in urls:
#     try:
#         st = time.time()  # Start time for performance measurement
#         # Create a RecursiveUrlLoader instance with a specified URL and depth
#         # The extractor function uses BeautifulSoup to parse the HTML content and extract text
#         loader = RecursiveUrlLoader(url=url, max_depth=5, extractor=lambda x: Soup(x, "html.parser").text)
        
#         # Load the documents from the URL and extend the docs list
#         docs.extend(loader.load())

#         et = time.time() - st  # Calculate time taken for splitting
#         print(f'Time taken for downloading documents from {url}: {et} seconds.')
#     except Exception as e:
#         # Print an error message if there is an issue with loading or parsing the URL
#         print(f"Failed to load or parse the URL {url}. Error: {e}", file=sys.stderr)
# etf = time.time() - stf  # Calculate time taken for splitting
# print(f'Total time taken for downloading {len(docs)} documents: {etf} seconds.')

# # Import necessary modules for text splitting and vectorization
# from langchain.text_splitter import RecursiveCharacterTextSplitter
# import time
# from langchain_community.vectorstores import FAISS
# from langchain.vectorstores.utils import filter_complex_metadata
# from langchain_community.embeddings import HuggingFaceEmbeddings

# # Configure the text splitter
# text_splitter = RecursiveCharacterTextSplitter(
#     separators=["\n\n", "\n", "(?<=\. )", " ", ""],  # Define the separators for splitting text
#     chunk_size=500,  # The size of each text chunk
#     chunk_overlap=50,  # Overlap between chunks to ensure continuity
#     length_function=len,  # Function to determine the length of each chunk
# )

# try:
#     # Stage one: Splitting the documents into chunks for vectorization
#     st = time.time()  # Start time for performance measurement
#     print('Loading documents and creating chunks ...')
#     # Split each document into chunks using the configured text splitter
#     chunks = text_splitter.create_documents([doc.page_content for doc in docs], metadatas=[doc.metadata for doc in docs])
#     et = time.time() - st  # Calculate time taken for splitting
#     print(f"created "+chunks+" chunks")
#     print(f'Time taken for document chunking: {et} seconds.')
# except Exception as e:
#     print(f"Error during document chunking: {e}", file=sys.stderr)

# # Path for saving the FAISS index
# FAISS_INDEX_PATH = "./vectorstore/lc-faiss-multi-mpnet-500"

# try:
#     # Stage two: Vectorization of the document chunks
#     model_name = "sentence-transformers/multi-qa-mpnet-base-dot-v1"  # Model used for embedding

#     # Initialize HuggingFace embeddings with the specified model
#     embeddings = HuggingFaceEmbeddings(model_name=model_name)

#     print(f'Loading chunks into vector store ...')
#     st = time.time()  # Start time for performance measurement
#     # Create a FAISS vector store from the document chunks and save it locally
#     db = FAISS.from_documents(filter_complex_metadata(chunks), embeddings)
#     db.save_local(FAISS_INDEX_PATH)
#     et = time.time() - st  # Calculate time taken for vectorization
#     print(f'Time taken for vectorization and saving: {et} seconds.')
# except Exception as e:
#     print(f"Error during vectorization or FAISS index saving: {e}", file=sys.stderr)

# alternatively download a preparaed vectorized index from S3 and load the index into vectorstore
# Import necessary libraries for AWS S3 interaction, file handling, and FAISS vector stores
import boto3
from botocore import UNSIGNED
from botocore.client import Config
import zipfile
from langchain_community.vectorstores import FAISS
from langchain_community.embeddings import HuggingFaceEmbeddings
from dotenv import load_dotenv

# Load environment variables from a .env file
config = load_dotenv(".env")

# Retrieve the Hugging Face API token from environment variables
HUGGINGFACEHUB_API_TOKEN = os.getenv('HUGGINGFACEHUB_API_TOKEN')
S3_LOCATION = os.getenv("S3_LOCATION")

try:
    # Initialize an S3 client with unsigned configuration for public access
    s3 = boto3.client('s3', config=Config(signature_version=UNSIGNED))

    # Define the FAISS index path and the destination for the downloaded file
    FAISS_INDEX_PATH = './vectorstore/lc-faiss-multi-mpnet-500-markdown'
    VS_DESTINATION = FAISS_INDEX_PATH + ".zip"

    # Download the pre-prepared vectorized index from the S3 bucket
    print("Downloading the pre-prepared vectorized index from S3...")
    s3.download_file(S3_LOCATION, 'vectorstores/lc-faiss-multi-mpnet-500-markdown.zip', VS_DESTINATION)

    # Extract the downloaded zip file
    with zipfile.ZipFile(VS_DESTINATION, 'r') as zip_ref:
        zip_ref.extractall('./vectorstore/')
    print("Download and extraction completed.")
    
except Exception as e:
    print(f"Error during downloading or extracting from S3: {e}", file=sys.stderr)

# Define the model name for embeddings
model_name = "sentence-transformers/multi-qa-mpnet-base-dot-v1"

try:
    # Initialize HuggingFace embeddings with the specified model
    embeddings = HuggingFaceEmbeddings(model_name=model_name)

    # Load the local FAISS index with the specified embeddings
    db = FAISS.load_local(FAISS_INDEX_PATH, embeddings)
    print("FAISS index loaded successfully.")
except Exception as e:
    print(f"Error during FAISS index loading: {e}", file=sys.stderr)

# Import necessary modules for environment variable management and HuggingFace integration
from langchain_community.llms import HuggingFaceHub

# Initialize the vector store as a retriever for the RAG pipeline
retriever = db.as_retriever()

try:
    # Load the model from the Hugging Face Hub
    model_id = HuggingFaceHub(repo_id="mistralai/Mixtral-8x7B-Instruct-v0.1", model_kwargs={
        "temperature": 0.1,         # Controls randomness in response generation (lower value means less random)
        "max_new_tokens": 1024,     # Maximum number of new tokens to generate in responses
        "repetition_penalty": 1.2,  # Penalty for repeating the same words (higher value increases penalty)
        "return_full_text": False   # If False, only the newly generated text is returned; if True, the input is included as well
    })
    print("Model loaded successfully from Hugging Face Hub.")
except Exception as e:
    print(f"Error loading model from Hugging Face Hub: {e}", file=sys.stderr)



# Importing necessary modules for retrieval-based question answering and prompt handling
from langchain.chains import RetrievalQA
from langchain.prompts import PromptTemplate
from langchain.memory import ConversationBufferMemory

# Declare a global variable 'qa' for the retrieval-based question answering system
global qa

# Define a prompt template for guiding the model's responses
template = """
You are the friendly documentation buddy Arti, if you don't know the answer say 'I don't know' and don't make things up.\
    Use the following context (delimited by <ctx></ctx>) and the chat history (delimited by <hs></hs>) to answer the question :
------
<ctx>
{context}
</ctx>
------
<hs>
{history}
</hs>
------
{question}
Answer:
"""

# Create a PromptTemplate object with specified input variables and the defined template
prompt = PromptTemplate.from_template(
    #input_variables=["history", "context", "question"],  # Variables to be included in the prompt
    template=template,  # The prompt template as defined above
)
prompt.format(context="context", history="history", question="question")
# Create a memory buffer to manage conversation history
memory = ConversationBufferMemory(
    memory_key="history",  # Key for storing the conversation history
    input_key="question"  # Key for the input question
)

# Initialize the RetrievalQA object with the specified model, retriever, and additional configurations
qa = RetrievalQA.from_chain_type(
    llm=model_id,  # Language model loaded from Hugging Face Hub
    retriever=retriever,  # The vector store retriever initialized earlier
    return_source_documents=True,  # Option to return source documents along with responses
    chain_type_kwargs={
        "verbose": True,  # Enables verbose output for debugging and analysis
        "memory": memory,  # Memory buffer for managing conversation history
        "prompt": prompt  # Prompt template for guiding the model's responses
    }
)

# Import Gradio for UI, along with other necessary libraries
import gradio as gr
import random
import time

# Function to add a new input to the chat history
def add_text(history, text):
    # Append the new text to the history with a placeholder for the response
    history = history + [(text, None)]
    return history, ""

# Function representing the bot's response mechanism
def bot(history):
    # Obtain the response from the 'infer' function using the latest input
    response = infer(history[-1][0], history)
    # Update the history with the bot's response
    history[-1][1] = response['result']
    return history

# Function to infer the response using the RAG model
def infer(question, history):
    # Use the question and history to query the RAG model
    result = qa({"query": question, "history": history, "question": question})
    return result

# CSS styling for the Gradio interface
css = """
#col-container {max-width: 700px; margin-left: auto; margin-right: auto;}
"""

# HTML content for the Gradio interface title
title = """
<div style="text-align: center;max-width: 700px;">
    <h1>Chat with your Documentation</h1>
    <p style="text-align: center;">Chat with LangChain Documentation, <br />
    You can ask questions about the LangChain docu ;)</p>
</div>
"""

# Building the Gradio interface
with gr.Blocks(css=css) as demo:
    with gr.Column(elem_id="col-container"):
        gr.HTML(title)  # Add the HTML title to the interface
        chatbot = gr.Chatbot([], elem_id="chatbot")  # Initialize the chatbot component
        clear = gr.Button("Clear")  # Add a button to clear the chat

        # Create a row for the question input
        with gr.Row():
            question = gr.Textbox(label="Question", placeholder="Type your question and hit Enter ")

    # Define the action when the question is submitted
    question.submit(add_text, [chatbot, question], [chatbot, question], queue=False).then(
        bot, chatbot, chatbot
    )
    # Define the action for the clear button
    clear.click(lambda: None, None, chatbot, queue=False)

# Launch the Gradio demo interface
demo.launch(share=False)