z_embedding.py

from typing import List, Optional
from uuid import uuid4
from langchain.text_splitter import RecursiveCharacterTextSplitter
from transformers import AutoTokenizer
from langchain.docstore.document import Document as LangchainDocument
from tqdm import tqdm

from langchain.vectorstores import FAISS
from langchain_community.embeddings import HuggingFaceEmbeddings
from langchain_community.vectorstores.utils import DistanceStrategy

from z_document_reader import read_wiki_html

EMBEDDING_MODEL_NAME = "thenlper/gte-small"

def get_embedding_model():

    embedding_model = HuggingFaceEmbeddings(
        model_name=EMBEDDING_MODEL_NAME,
        multi_process=True,
        model_kwargs={"device": "cpu"},
        encode_kwargs={"normalize_embeddings": True},  # Set `True` for cosine similarity
    )
    return embedding_model

def split_documents(
    chunk_size: int,
    knowledge_base: List[LangchainDocument],
    tokenizer_name: Optional[str] = EMBEDDING_MODEL_NAME,
) -> List[LangchainDocument]:
    """
    Split documents into chunks of maximum size `chunk_size` tokens and return a list of documents.
    """
    text_splitter = RecursiveCharacterTextSplitter.from_huggingface_tokenizer(
        AutoTokenizer.from_pretrained(tokenizer_name),
        chunk_size=chunk_size,
        chunk_overlap=int(chunk_size / 10),
        add_start_index=True,
        strip_whitespace=True,
        # separators=MARKDOWN_SEPARATORS,
    )

    docs_processed = []
    for doc in knowledge_base:
        docs_processed += text_splitter.split_documents([doc])

    # Remove duplicates
    unique_texts = {}
    docs_processed_unique = []
    for doc in docs_processed:
        if doc.page_content not in unique_texts:
            unique_texts[doc.page_content] = True
            docs_processed_unique.append(doc)

    return docs_processed_unique

def construct_vector_db(docs_processed, emb_model):
    vdb = FAISS.from_documents(
        docs_processed, emb_model, distance_strategy=DistanceStrategy.COSINE    
    )
    return vdb
    # from langchain_chroma import Chroma
    # vector_store = Chroma(
    #     collection_name="example_collection",
    #     embedding_function=emb_model,
    #     persist_directory="./chroma_langchain_db",  # Where to save data locally, remove if not necessary
    # )
    # return vector_store

def get_data_files(location:str ="_data/") -> list:
    """
    Returns html file paths
    """
    from glob import glob 
    files = glob(location + "*.html")
    files += glob(location + "*.htm")
    return files

def generate_and_save_vector_store(vector_store_location:str="cache_vector_store"):
    """
    One time function to create and store vector 
    """
    data_files = get_data_files()
    TEXT_KBs, IMAGE_KBs = list(), list() 
    for file in data_files: 
        TEXT_KB, IMAGE_KB = read_wiki_html(file) 
        TEXT_KBs.extend(TEXT_KB) 
        IMAGE_KBs.extend(IMAGE_KB)
    
    #
    docs_text_processed = split_documents(
        512,  # We choose a chunk size adapted to our model
        TEXT_KBs,
        tokenizer_name=EMBEDDING_MODEL_NAME,
    )
    docs_imgs_processed = split_documents(
        512,  # We choose a chunk size adapted to our model
        IMAGE_KBs,
        tokenizer_name=EMBEDDING_MODEL_NAME,
    )

    emb_model = get_embedding_model() 

    vector_store_text = construct_vector_db(docs_text_processed, emb_model)
    vector_store_images = construct_vector_db(docs_imgs_processed, emb_model)

    vector_store_text.save_local(vector_store_location+"_text")
    vector_store_images.save_local(vector_store_location+"_images")

def load_vector_store(vector_store_location:str="cache_vector_store"):
    '''Returns two vector stores; one for text and another for image
    '''
    emb_model = get_embedding_model()

    vs_text = FAISS.load_local(
        vector_store_location+"_text", emb_model, allow_dangerous_deserialization=True
    )
    vs_image = FAISS.load_local(
        vector_store_location+"_images", emb_model, allow_dangerous_deserialization=True
    )

    return vs_text, vs_image

if __name__ == "__main__":
    # generate_and_save_vector_store()
    load_vector_store()
    pass