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LangChain and PyPDF in RAG

PDF Extraction 🗂️📄

Step: Use PyPDF to extract text from PDF documents.

Process:

def extract_text_from_pdf(pdf_path):

    reader = PdfReader(pdf_path)

    text = ""

    for page in reader.pages:

        text += page.extract_text()

    return text

Explanation: PyPDF 📄🔍 goes through each page and extracts the text 📝 from the PDF 📂.


Document Indexing 🗂️📚

Step: Index the extracted text for efficient retrieval.

def index_text(text):

    index = faiss.IndexFlatL2(512)  # Creating an index

    embeddings = embed_text(text)   # Convert text to embeddings

    index.add(embeddings)           # Add embeddings to the index

    return index

Explanation: The text 📝 is converted to embeddings (vector representations) 🔢 and indexed 📚 using FAISS for quick retrieval 🔍.


Query Processing 🤖🔍

Step: Use LangChain to handle the sequence of operations: query processing, document retrieval, and response generation.

Process:

def create_response_chain():

    llm = OpenAI(model_name="gpt-3.5-turbo")  # Choose the LLM

    chain = LLMChain(llm=llm)                 # Create the chain

    return chain

Explanation: LangChain 🤖 manages the sequence of operations to process the query ❓, retrieve relevant documents 📚, and generate a response 💬.


Response Generation 📝✨

Step: Generate a response based on the retrieved text.

Process:

pdf_path = "example.pdf"

text = extract_text_from_pdf(pdf_path)

index = index_text(text)

chain = create_response_chain()

query = "What is the main topic of the document?"

response = chain.run(input={"query": query, "index": index})

print(response)

Explanation: The user's query ❓ is processed by LangChain 🤖, which retrieves relevant text passages 📚 and uses the LLM 📝 to generate a coherent response ✨.

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