add: GemmaTokenizer example
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examples/lightrag_gemini_demo_no_tiktoken.py
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223
examples/lightrag_gemini_demo_no_tiktoken.py
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# pip install -q -U google-genai to use gemini as a client
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import os
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from typing import Optional
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import dataclasses
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from pathlib import Path
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import hashlib
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import numpy as np
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from google import genai
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from google.genai import types
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from dotenv import load_dotenv
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from lightrag.utils import EmbeddingFunc, Tokenizer
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from lightrag import LightRAG, QueryParam
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from sentence_transformers import SentenceTransformer
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from lightrag.kg.shared_storage import initialize_pipeline_status
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import sentencepiece as spm
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import requests
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import asyncio
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import nest_asyncio
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# Apply nest_asyncio to solve event loop issues
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nest_asyncio.apply()
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load_dotenv()
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gemini_api_key = os.getenv("GEMINI_API_KEY")
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WORKING_DIR = "./dickens"
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if os.path.exists(WORKING_DIR):
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import shutil
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shutil.rmtree(WORKING_DIR)
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os.mkdir(WORKING_DIR)
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class GemmaTokenizer(Tokenizer):
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# adapted from google-cloud-aiplatform[tokenization]
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@dataclasses.dataclass(frozen=True)
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class _TokenizerConfig:
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tokenizer_model_url: str
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tokenizer_model_hash: str
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_TOKENIZERS = {
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"google/gemma2": _TokenizerConfig(
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tokenizer_model_url="https://raw.githubusercontent.com/google/gemma_pytorch/33b652c465537c6158f9a472ea5700e5e770ad3f/tokenizer/tokenizer.model",
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tokenizer_model_hash="61a7b147390c64585d6c3543dd6fc636906c9af3865a5548f27f31aee1d4c8e2",
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),
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"google/gemma3": _TokenizerConfig(
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tokenizer_model_url="https://raw.githubusercontent.com/google/gemma_pytorch/cb7c0152a369e43908e769eb09e1ce6043afe084/tokenizer/gemma3_cleaned_262144_v2.spiece.model",
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tokenizer_model_hash="1299c11d7cf632ef3b4e11937501358ada021bbdf7c47638d13c0ee982f2e79c",
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)
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}
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def __init__(self, model_name: str = "gemini-2.0-flash", tokenizer_dir: Optional[str] = None):
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# https://github.com/google/gemma_pytorch/tree/main/tokenizer
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if "1.5" in model_name or "1.0" in model_name:
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# up to gemini 1.5 gemma2 is a comparable local tokenizer
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# https://github.com/googleapis/python-aiplatform/blob/main/vertexai/tokenization/_tokenizer_loading.py
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tokenizer_name = "google/gemma2"
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else:
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# for gemini > 2.0 gemma3 was used
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tokenizer_name = "google/gemma3"
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file_url = self._TOKENIZERS[tokenizer_name].tokenizer_model_url
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tokenizer_model_name = file_url.rsplit("/", 1)[1]
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expected_hash = self._TOKENIZERS[tokenizer_name].tokenizer_model_hash
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tokenizer_dir = Path(tokenizer_dir)
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if tokenizer_dir.is_dir():
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file_path = tokenizer_dir / tokenizer_model_name
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model_data = self._maybe_load_from_cache(
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file_path=file_path, expected_hash=expected_hash
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)
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else:
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model_data = None
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if not model_data:
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model_data = self._load_from_url(file_url=file_url, expected_hash=expected_hash)
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self.save_tokenizer_to_cache(cache_path=file_path, model_data=model_data)
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tokenizer = spm.SentencePieceProcessor()
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tokenizer.LoadFromSerializedProto(model_data)
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super().__init__(model_name=model_name, tokenizer=tokenizer)
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def _is_valid_model(self, model_data: bytes, expected_hash: str) -> bool:
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"""Returns true if the content is valid by checking the hash."""
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return hashlib.sha256(model_data).hexdigest() == expected_hash
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def _maybe_load_from_cache(self, file_path: Path, expected_hash: str) -> bytes:
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"""Loads the model data from the cache path."""
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if not file_path.is_file():
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return
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with open(file_path, "rb") as f:
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content = f.read()
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if self._is_valid_model(model_data=content, expected_hash=expected_hash):
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return content
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# Cached file corrupted.
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self._maybe_remove_file(file_path)
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def _load_from_url(self, file_url: str, expected_hash: str) -> bytes:
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"""Loads model bytes from the given file url."""
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resp = requests.get(file_url)
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resp.raise_for_status()
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content = resp.content
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if not self._is_valid_model(model_data=content, expected_hash=expected_hash):
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actual_hash = hashlib.sha256(content).hexdigest()
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raise ValueError(
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f"Downloaded model file is corrupted."
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f" Expected hash {expected_hash}. Got file hash {actual_hash}."
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)
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return content
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@staticmethod
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def save_tokenizer_to_cache(cache_path: Path, model_data: bytes) -> None:
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"""Saves the model data to the cache path."""
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try:
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if not cache_path.is_file():
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cache_dir = cache_path.parent
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cache_dir.mkdir(parents=True, exist_ok=True)
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with open(cache_path, "wb") as f:
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f.write(model_data)
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except OSError:
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# Don't raise if we cannot write file.
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pass
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@staticmethod
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def _maybe_remove_file(file_path: Path) -> None:
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"""Removes the file if exists."""
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if not file_path.is_file():
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return
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try:
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file_path.unlink()
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except OSError:
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# Don't raise if we cannot remove file.
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pass
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# def encode(self, content: str) -> list[int]:
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# return self.tokenizer.encode(content)
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# def decode(self, tokens: list[int]) -> str:
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# return self.tokenizer.decode(tokens)
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async def llm_model_func(
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prompt, system_prompt=None, history_messages=[], keyword_extraction=False, **kwargs
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) -> str:
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# 1. Initialize the GenAI Client with your Gemini API Key
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client = genai.Client(api_key=gemini_api_key)
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# 2. Combine prompts: system prompt, history, and user prompt
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if history_messages is None:
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history_messages = []
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combined_prompt = ""
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if system_prompt:
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combined_prompt += f"{system_prompt}\n"
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for msg in history_messages:
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# Each msg is expected to be a dict: {"role": "...", "content": "..."}
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combined_prompt += f"{msg['role']}: {msg['content']}\n"
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# Finally, add the new user prompt
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combined_prompt += f"user: {prompt}"
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# 3. Call the Gemini model
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response = client.models.generate_content(
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model="gemini-1.5-flash",
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contents=[combined_prompt],
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config=types.GenerateContentConfig(max_output_tokens=500, temperature=0.1),
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)
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# 4. Return the response text
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return response.text
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async def embedding_func(texts: list[str]) -> np.ndarray:
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model = SentenceTransformer("all-MiniLM-L6-v2")
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embeddings = model.encode(texts, convert_to_numpy=True)
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return embeddings
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async def initialize_rag():
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rag = LightRAG(
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working_dir=WORKING_DIR,
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# tiktoken_model_name="gpt-4o-mini",
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tokenizer=GemmaTokenizer(tokenizer_dir=(Path(WORKING_DIR) / "vertexai_tokenizer_model"), model_name="gemini-2.0-flash"),
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llm_model_func=llm_model_func,
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embedding_func=EmbeddingFunc(
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embedding_dim=384,
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max_token_size=8192,
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func=embedding_func,
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),
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)
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await rag.initialize_storages()
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await initialize_pipeline_status()
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return rag
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def main():
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# Initialize RAG instance
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rag = asyncio.run(initialize_rag())
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file_path = "story.txt"
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with open(file_path, "r") as file:
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text = file.read()
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rag.insert(text)
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response = rag.query(
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query="What is the main theme of the story?",
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param=QueryParam(mode="hybrid", top_k=5, response_type="single line"),
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)
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print(response)
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if __name__ == "__main__":
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main()
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