use this retriver instead:
Parent Document Retriever

When splitting documents for retrieval, there are often conflicting desires:

    You may want to have small documents, so that their embeddings can most accurately reflect their meaning. If too long, then the embeddings can lose meaning.
    You want to have long enough documents that the context of each chunk is retained.

The ParentDocumentRetriever strikes that balance by splitting and storing small chunks of data. During retrieval, it first fetches the small chunks but then looks up the parent ids for those chunks and returns those larger documents.

Note that "parent document" refers to the document that a small chunk originated from. This can either be the whole raw document OR a larger chunk.

from langchain.retrievers import ParentDocumentRetriever

API Reference:

    ParentDocumentRetriever

from langchain.storage import InMemoryStore
from langchain_chroma import Chroma
from langchain_community.document_loaders import TextLoader
from langchain_openai import OpenAIEmbeddings
from langchain_text_splitters import RecursiveCharacterTextSplitter

API Reference:

    InMemoryStore
    TextLoader
    OpenAIEmbeddings
    RecursiveCharacterTextSplitter

loaders = [
    TextLoader("../../paul_graham_essay.txt"),
    TextLoader("../../state_of_the_union.txt"),
]
docs = []
for loader in loaders:
    docs.extend(loader.load())

Retrieving full documents

In this mode, we want to retrieve the full documents. Therefore, we only specify a child splitter.

# This text splitter is used to create the child documents
child_splitter = RecursiveCharacterTextSplitter(chunk_size=400)
# The vectorstore to use to index the child chunks
vectorstore = Chroma(
    collection_name="full_documents", embedding_function=OpenAIEmbeddings()
)
# The storage layer for the parent documents
store = InMemoryStore()
retriever = ParentDocumentRetriever(
    vectorstore=vectorstore,
    docstore=store,
    child_splitter=child_splitter,
)

retriever.add_documents(docs, ids=None)

This should yield two keys, because we added two documents.

list(store.yield_keys())

['cfdf4af7-51f2-4ea3-8166-5be208efa040',
 'bf213c21-cc66-4208-8a72-733d030187e6']

Let's now call the vector store search functionality - we should see that it returns small chunks (since we're storing the small chunks).

sub_docs = vectorstore.similarity_search("justice breyer")

print(sub_docs[0].page_content)

Tonight, I’d like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the United States Supreme Court. Justice Breyer, thank you for your service. 

One of the most serious constitutional responsibilities a President has is nominating someone to serve on the United States Supreme Court.

Let's now retrieve from the overall retriever. This should return large documents - since it returns the documents where the smaller chunks are located.

retrieved_docs = retriever.invoke("justice breyer")

len(retrieved_docs[0].page_content)

38540

Retrieving larger chunks

Sometimes, the full documents can be too big to want to retrieve them as is. In that case, what we really want to do is to first split the raw documents into larger chunks, and then split it into smaller chunks. We then index the smaller chunks, but on retrieval we retrieve the larger chunks (but still not the full documents).

# This text splitter is used to create the parent documents
parent_splitter = RecursiveCharacterTextSplitter(chunk_size=2000)
# This text splitter is used to create the child documents
# It should create documents smaller than the parent
child_splitter = RecursiveCharacterTextSplitter(chunk_size=400)
# The vectorstore to use to index the child chunks
vectorstore = Chroma(
    collection_name="split_parents", embedding_function=OpenAIEmbeddings()
)
# The storage layer for the parent documents
store = InMemoryStore()

retriever = ParentDocumentRetriever(
    vectorstore=vectorstore,
    docstore=store,
    child_splitter=child_splitter,
    parent_splitter=parent_splitter,
)

retriever.add_documents(docs)

We can see that there are much more than two documents now - these are the larger chunks.

len(list(store.yield_keys()))

66

Let's make sure the underlying vector store still retrieves the small chunks.

sub_docs = vectorstore.similarity_search("justice breyer")

print(sub_docs[0].page_content)

Tonight, I’d like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the United States Supreme Court. Justice Breyer, thank you for your service. 

One of the most serious constitutional responsibilities a President has is nominating someone to serve on the United States Supreme Court.

retrieved_docs = retriever.invoke("justice breyer")

len(retrieved_docs[0].page_content)

1849

print(retrieved_docs[0].page_content)

In state after state, new laws have been passed, not only to suppress the vote, but to subvert entire elections. 

We cannot let this happen. 

Tonight. I call on the Senate to: Pass the Freedom to Vote Act. Pass the John Lewis Voting Rights Act. And while you’re at it, pass the Disclose Act so Americans can know who is funding our elections. 

Tonight, I’d like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the United States Supreme Court. Justice Breyer, thank you for your service. 

One of the most serious constitutional responsibilities a President has is nominating someone to serve on the United States Supreme Court. 

And I did that 4 days ago, when I nominated Circuit Court of Appeals Judge Ketanji Brown Jackson. One of our nation’s top legal minds, who will continue Justice Breyer’s legacy of excellence. 

A former top litigator in private practice. A former federal public defender. And from a family of public school educators and police officers. A consensus builder. Since she’s been nominated, she’s received a broad range of support—from the Fraternal Order of Police to former judges appointed by Democrats and Republicans. 

And if we are to advance liberty and justice, we need to secure the Border and fix the immigration system. 

We can do both. At our border, we’ve installed new technology like cutting-edge scanners to better detect drug smuggling.  

We’ve set up joint patrols with Mexico and Guatemala to catch more human traffickers.  

We’re putting in place dedicated immigration judges so families fleeing persecution and violence can have their cases heard faster. 

We’re securing commitments and supporting partners in South and Central America to host more refugees and secure their own borders.

Help us out by providing feedback on this documentation page:



Code:
import os
import json
import shutil
import gradio as gr
from itertools import chain
from langchain_community.embeddings.sentence_transformer import SentenceTransformerEmbeddings
from langchain_unstructured import UnstructuredLoader
from langchain_core.messages import HumanMessage, SystemMessage, AIMessage
from langchain_text_splitters import CharacterTextSplitter
from langchain_community.vectorstores import Chroma
from langchain_community.retrievers import ArxivRetriever
from langchain_community.tools import DuckDuckGoSearchRun
from langchain_community.document_loaders import DirectoryLoader
from langchain_ollama import ChatOllama

# For LangSmith tracing
from langsmith import traceable
os.environ["LANGCHAIN_TRACING_V2"] = "true"
os.environ["LANGCHAIN_API_KEY"] = "<TRUFFLEHOG_REDACTED_LANGSMITH>"  # Replace with your actual API key
os.environ["LANGCHAIN_PROJECT"] = "l"  # Optional: "default" is used if not set

# Initialize embeddings and vector store
embeddings = SentenceTransformerEmbeddings(model_name="all-MiniLM-L6-v2")
persist_directory = "./chroma_db"
vectorstore = Chroma(persist_directory=persist_directory, embedding_function=embeddings)

# Ensure the 'uploads' directory exists
if not os.path.exists("uploads"):
    os.makedirs("uploads")

# Function to load or initialize knowledge base JSON
def load_knowledge_base_json():
    if os.path.exists("knowledge_base.json"):
        with open("knowledge_base.json", "r") as f:
            knowledge_base_data = json.load(f)
    else:
        knowledge_base_data = {"files": [], "urls": []}
    return knowledge_base_data

knowledge_base_data = load_knowledge_base_json()

# Function to save knowledge base JSON
def save_knowledge_base_json():
    with open("knowledge_base.json", "w") as f:
        json.dump(knowledge_base_data, f)

# Function to get processed files
def get_processed_files():
    files = os.listdir("uploads")
    return "### Processed Files:\n" + "\n".join(files) if files else "No files processed yet."

# Function to display processed files and URLs
def display_processed_items():
    global knowledge_base_data
    files_text = get_processed_files()
    urls = knowledge_base_data.get("urls", [])
    display_text = files_text + "\n\n### Processed URLs:\n"
    if urls:
        display_text += "\n".join(urls)
    else:
        display_text += "No URLs processed yet."
    return display_text

# Function to update the knowledge base
@traceable
def update_knowledge_base(uploaded_files, website_urls):
    global knowledge_base_data
    if not uploaded_files and not website_urls:
        return "No new documents or URLs to process.", display_processed_items()

    processed_files = []
    skipped_files = []
    docs = []
    new_urls = []

    # Process uploaded files
    if uploaded_files:
        for file in uploaded_files:
            file_path = file.name
            destination_path = os.path.join("uploads", os.path.basename(file_path))
            file_name = os.path.basename(file_path)

            if os.path.exists(destination_path) or file_name in knowledge_base_data["files"]:
                skipped_files.append(file_name)
            else:
                try:
                    shutil.move(file_path, destination_path)
                    processed_files.append(file_name)
                except Exception as e:
                    print(f"Error moving file {file_name}: {str(e)}")

    # Load documents from uploaded files
    if processed_files:
        loader = DirectoryLoader("uploads", glob="**/*")
        documents = loader.load()
        docs.extend(documents)

    # Load documents from URLs
    if website_urls:
        urls = website_urls.split(',')
        for url in urls:
            url = url.strip()
            if url and url not in knowledge_base_data["urls"]:
                loader = UnstructuredLoader(web_url=url)
                try:
                    loaded_docs = loader.load()
                    docs.extend(loaded_docs)
                    new_urls.append(url)
                except Exception as e:
                    print(f"Error loading URL {url}: {str(e)}")
            else:
                skipped_files.append(url)

    # Split documents and add to vector store
    if docs:
        text_splitter = CharacterTextSplitter(chunk_size=1000, chunk_overlap=200, length_function=len)
        split_docs = text_splitter.split_documents(docs)
        vectorstore.add_documents(split_docs)
        vectorstore.persist()
        # Update knowledge base data and save to JSON
        knowledge_base_data["files"].extend(processed_files)
        knowledge_base_data["urls"].extend(new_urls)
        save_knowledge_base_json()
        status_message = f"Processed {len(processed_files)} new files and {len(new_urls)} new URLs."
        if skipped_files:
            status_message += f"\nSkipped existing files/URLs: {', '.join(skipped_files)}"
    else:
        status_message = "No new documents or URLs were added."
    return status_message, display_processed_items()

# Function to clear database and uploaded files
def clear_database():
    global vectorstore, knowledge_base_data

    try:
        vectorstore._client._client.close()
    except AttributeError:
        pass

    shutil.rmtree("uploads", ignore_errors=True)
    os.makedirs("uploads", exist_ok=True)

    shutil.rmtree(persist_directory, ignore_errors=True)

    vectorstore = Chroma(persist_directory=persist_directory, embedding_function=embeddings)

    # Clear the knowledge base data
    knowledge_base_data = {"files": [], "urls": []}
    # Remove the JSON file
    if os.path.exists("knowledge_base.json"):
        os.remove("knowledge_base.json")

    return "Knowledge base and uploaded files cleared.", display_processed_items()

# Function to process uploaded files in the chat and include their content
def process_uploaded_files(files):
    content = ""
    if files:
        for file in files:
            if file.name.endswith((".pdf", ".txt", ".docx")):
                loader = UnstructuredLoader(file_path=file.name)
                try:
                    docs = loader.load()
                    content += "\n".join([doc.page_content for doc in docs])
                except Exception as e:
                    print(f"Error processing file {file.name}: {str(e)}")
    return content

# Function to count tokens
def count_tokens(text):
    return len(text.split())  # Simple token count; adjust with tokenizer if needed

# Initialize Llama model
llm = ChatOllama(
    model="llama3.1",
    temperature=0,
    base_url="http://localhost:11434",
    streaming=True
)

# Maximum token limit
MAX_TOKENS = 128000  # Example maximum token limit

# Chat with Llama (normal chat) function
@traceable
def chat_with_llama(message, history, uploaded_files):
    # Process uploaded files and include their content
    file_content = process_uploaded_files(uploaded_files)
    # Convert history to list of messages
    messages = [SystemMessage(content="You are a helpful assistant. The user is able to upload files that get processed as text for you. You always answer to the users question by using the context or your knowlage in the same language the user wants you to talk in.")]
    if history:
        for user_msg, assistant_msg in history:
            if user_msg:
                messages.append(HumanMessage(content=user_msg))
                if assistant_msg is not None:
                    messages.append(AIMessage(content=assistant_msg))
    # Append file content to user message if any
    if file_content:
        message += f"\n\nContent files Uploaded:\n{file_content}"
        message += "\n\nWith that knowlage answer to the question as best as possible: "
    messages.append(HumanMessage(content=message))
    # Append the Question at the end again
    # Check if the total tokens exceed the maximum allowed tokens
    total_tokens = sum(count_tokens(msg.content) for msg in messages)
    if total_tokens > MAX_TOKENS:
        # Truncate the history to fit within the token limit
        while total_tokens > MAX_TOKENS and len(messages) > 2:
            # Remove the oldest user-assistant message pair
            messages.pop(1)
            messages.pop(1)
            total_tokens = sum(count_tokens(msg.content) for msg in messages)
        if total_tokens > MAX_TOKENS:
            return "Error: The conversation exceeds the maximum token limit. Please start a new chat."
    # Stream the response from the model
    try:
        response_stream = llm.stream(messages)
        partial_response = ""
        for chunk in response_stream:
            partial_response += chunk.content
            yield partial_response
    except Exception as e:
        yield f"Error: {str(e)}"

# Function to handle knowledge base Q&A using similarity search
@traceable
def knowledge_base_chat(message, history):
    # Search in the vector store using similarity search
    results = vectorstore.similarity_search(message, k=3)
    if not results:
        yield "No relevant information found in the knowledge base."
        return
    context = "\n\n".join([doc.page_content for doc in results])
    # Build the conversation history
    messages = [SystemMessage(content="You are a helpful assistant that answers questions based on the provided context.")]
    if history:
        for user_msg, assistant_msg in history:
            if user_msg:
                messages.append(HumanMessage(content=user_msg))
                if assistant_msg is not None:
                    messages.append(AIMessage(content=assistant_msg))
    # Add the latest message with context
    prompt = f"Context:\n{context}\n\nQuestion:\n{message}\n\nAnswer:"
    messages.append(HumanMessage(content=prompt))
    # Stream the response from the model
    try:
        response_stream = llm.stream(messages)
        partial_response = ""
        for chunk in response_stream:
            partial_response += chunk.content
            # Use yield to stream the response
            yield partial_response
    except Exception as e:
        yield f"Error: {str(e)}"

# Function for the Internet-Enabled LLM
@traceable
def internet_access_llm(message, history, use_wikipedia):
    # Generate a query from the user input
    query = message
    # Search the internet
    search_tool = DuckDuckGoSearchRun()
    search_results = search_tool.invoke(query)
    # Optionally search Wikipedia
    if use_wikipedia:
        wikipedia_tool = DuckDuckGoSearchRun(backend="wikipedia")
        wiki_results = wikipedia_tool.invoke(query)
        search_results += "\n\n" + wiki_results
    # Build the conversation history
    messages = [SystemMessage(content="You get information from the internet and answer the user's question with that information. Provide an accurate and detailed answer to the user's question using the search results.")]
    if history:
        for user_msg, assistant_msg in history:
            if user_msg:
                messages.append(HumanMessage(content=user_msg))
                if assistant_msg is not None:
                    messages.append(AIMessage(content=assistant_msg))
    # Add the latest message with search results
    prompt = f"Search Results:\n{search_results}\n\nQuestion:\n{message}\n\nAnswer:"
    messages.append(HumanMessage(content=prompt))
    # Stream the response from the model
    try:
        response_stream = llm.stream(messages)
        partial_response = ""
        for chunk in response_stream:
            partial_response += chunk.content
            yield partial_response
    except Exception as e:
        yield f"Error: {str(e)}"

# Function to retrieve arXiv papers and update knowledge base
@traceable
def arxiv_research(query, max_papers):
    global knowledge_base_data
    retriever = ArxivRetriever(load_max_docs=int(max_papers), get_full_documents=True)
    docs = retriever.get_relevant_documents(query)
    # Add documents to the vector store
    if docs:
        text_splitter = CharacterTextSplitter(chunk_size=1000, chunk_overlap=200, length_function=len)
        split_docs = text_splitter.split_documents(docs)
        vectorstore.add_documents(split_docs)
        vectorstore.persist()
        # Update knowledge base data and save to JSON
        arxiv_titles = [doc.metadata.get('Title', 'Unknown Title') for doc in docs]
        knowledge_base_data["files"].extend(arxiv_titles)
        save_knowledge_base_json()
        status_message = f"Added {len(docs)} papers to the knowledge base."
    else:
        status_message = "No documents were added from arXiv."
    return status_message, display_processed_items()

# Function to handle arXiv Knowledge Base Q&A using similarity search
@traceable
def ask_arxiv_knowledge_base(message, history):
    # Search in the vector store using similarity search
    results = vectorstore.similarity_search(message, k=3)
    if not results:
        yield "No relevant information found in the arXiv knowledge base."
        return
    context = "\n\n".join([doc.page_content for doc in results])
    # Build the conversation history
    messages = [SystemMessage(content="You are a helpful assistant that answers questions based on arXiv research papers.")]
    if history:
        for user_msg, assistant_msg in history:
            if user_msg:
                messages.append(HumanMessage(content=user_msg))
                if assistant_msg is not None:
                    messages.append(AIMessage(content=assistant_msg))
    # Add the latest message with context
    prompt = f"Context:\n{context}\n\nQuestion:\n{message}\n\nAnswer:"
    messages.append(HumanMessage(content=prompt))
    # Stream the response from the model
    try:
        response_stream = llm.stream(messages)
        partial_response = ""
        for chunk in response_stream:
            partial_response += chunk.content
            yield partial_response
    except Exception as e:
        yield f"Error: {str(e)}"

# Gradio interface
with gr.Blocks() as demo:
    gr.Markdown("# Multi-Tab Gradio App with Llama and Similarity Search")

    # Chat with Llama Tab
    with gr.Tab("Chat with Llama"):
        gr.Markdown("## Chat Interface")
        with gr.Row():
            upload_files = gr.File(
                label="Upload PDFs, DOCX or TXT files",
                file_types=[".pdf", ".txt", ".docx"],
                file_count="multiple",
                visible=True
            )
        gr_chat = gr.ChatInterface(
            fn=chat_with_llama,
            title="Chat with Llama",
            fill_height=True,  # Use fill_height instead of height
            additional_inputs=[upload_files]
        )

    # Knowledge Base Tab
    with gr.Tab("Knowledge Base"):
        gr.Markdown("## Knowledge Base Management and Chat")
        with gr.Row():
            with gr.Column(scale=1):
                gr.Markdown("### Update Knowledge Base")
                kb_upload_files = gr.File(
                    label="Upload Files",
                    file_types=[".pdf", ".txt", ".docx"],
                    file_count="multiple"
                )
                kb_website_urls = gr.Textbox(
                    label="Website URLs",
                    placeholder="Enter comma-separated URLs"
                )
                kb_update_button = gr.Button("Update Knowledge Base")
                kb_clear_button = gr.Button("Clear Database")
                kb_update_status = gr.Markdown()
                kb_update_button.click(
                    update_knowledge_base,
                    inputs=[kb_upload_files, kb_website_urls],
                    outputs=[kb_update_status, kb_update_status]
                )
                kb_clear_button.click(
                    clear_database,
                    outputs=[kb_update_status, kb_update_status]
                )
                gr.Markdown("### Processed Files and URLs")
                processed_items_display = gr.Markdown(display_processed_items())
                # Update the display when the knowledge base is updated or cleared
                kb_update_button.click(
                    update_knowledge_base,
                    inputs=[kb_upload_files, kb_website_urls],
                    outputs=[kb_update_status, processed_items_display]
                )
                kb_clear_button.click(
                    clear_database,
                    outputs=[kb_update_status, processed_items_display]
                )
            with gr.Column(scale=2):
                gr.Markdown("### Chat with Knowledge Base")
                gr_chat_kb = gr.ChatInterface(
                    fn=knowledge_base_chat,
                    title="Knowledge Base Chat",
                    fill_height=True  # Use fill_height instead of height
                )

    # LLM with Internet Access Tab
    with gr.Tab("LLM with Internet Access"):
        gr.Markdown("## Internet-Enabled LLM")
        use_wikipedia = gr.Checkbox(label="Use Wikipedia")
        gr_chat_internet = gr.ChatInterface(
            fn=internet_access_llm,
            title="LLM with Internet Access",
            additional_inputs=[use_wikipedia],
            fill_height=True  # Use fill_height instead of height
        )

    # arXiv Research Papers Tab
    with gr.Tab("arXiv Research Papers"):
        gr.Markdown("## Retrieve arXiv Papers and Chat")
        with gr.Row():
            with gr.Column(scale=1):
                gr.Markdown("### Retrieve arXiv Papers")
                arxiv_query = gr.Textbox(
                    label="Search Query",
                    placeholder="Enter your search query for arXiv papers"
                )
                max_papers = gr.Slider(
                    label="Number of Papers",
                    minimum=1,
                    maximum=10,
                    step=1,
                    value=5
                )
                arxiv_button = gr.Button("Retrieve Papers")
                arxiv_result = gr.Markdown()
                arxiv_button.click(
                    arxiv_research,
                    inputs=[arxiv_query, max_papers],
                    outputs=[arxiv_result, arxiv_result]
                )
                gr.Markdown("### Processed Files and URLs")
                processed_items_display_arxiv = gr.Markdown(display_processed_items())
                # Update the display when new papers are added
                arxiv_button.click(
                    arxiv_research,
                    inputs=[arxiv_query, max_papers],
                    outputs=[arxiv_result, processed_items_display_arxiv]
                )
            with gr.Column(scale=2):
                gr.Markdown("### Chat with arXiv Knowledge Base")
                gr_chat_arxiv = gr.ChatInterface(
                    fn=ask_arxiv_knowledge_base,
                    title="arXiv Knowledge Base Chat",
                    fill_height=True  # Use fill_height instead of height
                )

    # Apply CSS styling to adjust chatbox sizes if needed
    # Uncomment and adjust the CSS if 'fill_height' doesn't work as expected
    """
    demo.css = '''
    .gradio-chatbot {
        height: 600px !important;
    }
    '''
    """

    # Launch the app
    demo.launch()