mirror of https://github.com/hwchase17/langchain
New LLM integration: Ctranslate2 (#10400)
## Description: I've integrated CTranslate2 with LangChain. CTranlate2 is a recently popular library for efficient inference with Transformer models that compares favorably to alternatives such as HF Text Generation Inference and vLLM in [benchmarks](https://hamel.dev/notes/llm/inference/03_inference.html).pull/10412/head
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from typing import Any, Dict, List, Optional, Union
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from langchain.callbacks.manager import CallbackManagerForLLMRun
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from langchain.llms.base import BaseLLM
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from langchain.pydantic_v1 import Field, root_validator
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from langchain.schema.output import Generation, LLMResult
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class CTranslate2(BaseLLM):
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"""CTranslate2 language model."""
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model_path: str = ""
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"""Path to the CTranslate2 model directory."""
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tokenizer_name: str = ""
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"""Name of the original Hugging Face model needed to load the proper tokenizer."""
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device: str = "cpu"
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"""Device to use (possible values are: cpu, cuda, auto)."""
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device_index: Union[int, List[int]] = 0
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"""Device IDs where to place this generator on."""
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compute_type: Union[str, Dict[str, str]] = "default"
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"""
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Model computation type or a dictionary mapping a device name to the computation type
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(possible values are: default, auto, int8, int8_float32, int8_float16,
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int8_bfloat16, int16, float16, bfloat16, float32).
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"""
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max_length: int = 512
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"""Maximum generation length."""
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sampling_topk: int = 1
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"""Randomly sample predictions from the top K candidates."""
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sampling_topp: float = 1
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"""Keep the most probable tokens whose cumulative probability exceeds this value."""
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sampling_temperature: float = 1
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"""Sampling temperature to generate more random samples."""
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client: Any #: :meta private:
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tokenizer: Any #: :meta private:
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ctranslate2_kwargs: Dict[str, Any] = Field(default_factory=dict)
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"""
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Holds any model parameters valid for `ctranslate2.Generator` call not
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explicitly specified.
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"""
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@root_validator()
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def validate_environment(cls, values: Dict) -> Dict:
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"""Validate that python package exists in environment."""
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try:
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import ctranslate2
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except ImportError:
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raise ImportError(
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"Could not import ctranslate2 python package. "
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"Please install it with `pip install ctranslate2`."
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)
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try:
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import transformers
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except ImportError:
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raise ImportError(
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"Could not import transformers python package. "
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"Please install it with `pip install transformers`."
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)
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values["client"] = ctranslate2.Generator(
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model_path=values["model_path"],
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device=values["device"],
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device_index=values["device_index"],
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compute_type=values["compute_type"],
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**values["ctranslate2_kwargs"],
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)
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values["tokenizer"] = transformers.AutoTokenizer.from_pretrained(
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values["tokenizer_name"]
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)
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return values
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@property
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def _default_params(self) -> Dict[str, Any]:
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"""Get the default parameters."""
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return {
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"max_length": self.max_length,
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"sampling_topk": self.sampling_topk,
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"sampling_topp": self.sampling_topp,
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"sampling_temperature": self.sampling_temperature,
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}
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def _generate(
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self,
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prompts: List[str],
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stop: Optional[List[str]] = None,
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run_manager: Optional[CallbackManagerForLLMRun] = None,
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**kwargs: Any,
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) -> LLMResult:
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# build sampling parameters
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params = {**self._default_params, **kwargs}
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# call the model
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encoded_prompts = self.tokenizer(prompts)["input_ids"]
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tokenized_prompts = [
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self.tokenizer.convert_ids_to_tokens(encoded_prompt)
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for encoded_prompt in encoded_prompts
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]
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results = self.client.generate_batch(tokenized_prompts, **params)
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sequences = [result.sequences_ids[0] for result in results]
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decoded_sequences = [self.tokenizer.decode(seq) for seq in sequences]
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generations = []
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for text in decoded_sequences:
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generations.append([Generation(text=text)])
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return LLMResult(generations=generations)
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@property
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def _llm_type(self) -> str:
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"""Return type of llm."""
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return "ctranslate2"
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