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| from typing import Union | |
| import numpy as np | |
| import torch | |
| import transformers | |
| from transformers import AutoModelForCausalLM, AutoTokenizer | |
| from config import huggingface_config | |
| from .utils import assert_tokenizer_consistency | |
| from .metrics import perplexity, entropy | |
| torch.set_grad_enabled(False) | |
| # selected using Falcon-7B and Falcon-7B-Instruct at bfloat16 | |
| BINOCULARS_ACCURACY_THRESHOLD = 0.9015310749276843 # optimized for f1-score | |
| BINOCULARS_FPR_THRESHOLD = 0.8536432310785527 # optimized for low-fpr | |
| DEVICE_1 = "cuda:0" if torch.cuda.is_available() else "cpu" | |
| DEVICE_2 = "cuda:1" if torch.cuda.device_count() > 1 else DEVICE_1 | |
| class Binoculars(object): | |
| def __init__(self, | |
| observer_name_or_path: str = "tiiuae/falcon-7b", | |
| performer_name_or_path: str = "tiiuae/falcon-7b-instruct", | |
| use_bfloat16: bool = True, | |
| max_token_observed: int = 512, | |
| mode: str = "low-fpr", | |
| ) -> None: | |
| assert_tokenizer_consistency(observer_name_or_path, performer_name_or_path) | |
| if mode == "low-fpr": | |
| self.threshold = BINOCULARS_FPR_THRESHOLD | |
| elif mode == "accuracy": | |
| self.threshold = BINOCULARS_ACCURACY_THRESHOLD | |
| else: | |
| raise ValueError(f"Invalid mode: {mode}") | |
| self.observer_model = AutoModelForCausalLM.from_pretrained(observer_name_or_path, | |
| device_map={"": DEVICE_1}, | |
| trust_remote_code=True, | |
| torch_dtype=torch.bfloat16 if use_bfloat16 | |
| else torch.float32, | |
| token=huggingface_config["TOKEN"] | |
| ) | |
| self.performer_model = AutoModelForCausalLM.from_pretrained(performer_name_or_path, | |
| device_map={"": DEVICE_2}, | |
| trust_remote_code=True, | |
| torch_dtype=torch.bfloat16 if use_bfloat16 | |
| else torch.float32, | |
| token=huggingface_config["TOKEN"] | |
| ) | |
| self.observer_model.eval() | |
| self.performer_model.eval() | |
| self.tokenizer = AutoTokenizer.from_pretrained(observer_name_or_path) | |
| if not self.tokenizer.pad_token: | |
| self.tokenizer.pad_token = self.tokenizer.eos_token | |
| self.max_token_observed = max_token_observed | |
| def change_mode(self, mode: str) -> None: | |
| if mode == "low-fpr": | |
| self.threshold = BINOCULARS_FPR_THRESHOLD | |
| elif mode == "accuracy": | |
| self.threshold = BINOCULARS_ACCURACY_THRESHOLD | |
| else: | |
| raise ValueError(f"Invalid mode: {mode}") | |
| def _tokenize(self, batch: list[str]) -> transformers.BatchEncoding: | |
| batch_size = len(batch) | |
| encodings = self.tokenizer( | |
| batch, | |
| return_tensors="pt", | |
| padding="longest" if batch_size > 1 else False, | |
| truncation=True, | |
| max_length=self.max_token_observed, | |
| return_token_type_ids=False).to(self.observer_model.device) | |
| return encodings | |
| def _get_logits(self, encodings: transformers.BatchEncoding) -> torch.Tensor: | |
| observer_logits = self.observer_model(**encodings.to(DEVICE_1)).logits | |
| performer_logits = self.performer_model(**encodings.to(DEVICE_2)).logits | |
| if DEVICE_1 != "cpu": | |
| torch.cuda.synchronize() | |
| return observer_logits, performer_logits | |
| def compute_score(self, input_text: Union[list[str], str]) -> Union[float, list[float]]: | |
| batch = [input_text] if isinstance(input_text, str) else input_text | |
| encodings = self._tokenize(batch) | |
| observer_logits, performer_logits = self._get_logits(encodings) | |
| ppl = perplexity(encodings, performer_logits) | |
| x_ppl = entropy(observer_logits.to(DEVICE_1), performer_logits.to(DEVICE_1), | |
| encodings.to(DEVICE_1), self.tokenizer.pad_token_id) | |
| binoculars_scores = ppl / x_ppl | |
| binoculars_scores = binoculars_scores.tolist() | |
| return binoculars_scores[0] if isinstance(input_text, str) else binoculars_scores | |
| def predict(self, input_text: Union[list[str], str]) -> Union[list[str], str]: | |
| binoculars_scores = np.array(self.compute_score(input_text)) | |
| pred = np.where(binoculars_scores < self.threshold, | |
| "Most likely AI-generated", | |
| "Most likely human-generated" | |
| ).tolist() | |
| return pred | |