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| import torch | |
| from sacrebleu import corpus_bleu | |
| from rouge_score import rouge_scorer | |
| from bert_score import score | |
| from transformers import GPT2LMHeadModel, GPT2Tokenizer, pipeline | |
| import nltk | |
| from nltk.util import ngrams | |
| class RAGEvaluator: | |
| def __init__(self): | |
| self.gpt2_model, self.gpt2_tokenizer = self.load_gpt2_model() | |
| self.bias_pipeline = pipeline("zero-shot-classification", model="Hate-speech-CNERG/dehatebert-mono-english") | |
| def load_gpt2_model(self): | |
| model = GPT2LMHeadModel.from_pretrained('gpt2') | |
| tokenizer = GPT2Tokenizer.from_pretrained('gpt2') | |
| return model, tokenizer | |
| def evaluate_bleu_rouge(self, candidates, references): | |
| bleu_score = corpus_bleu(candidates, [references]).score | |
| scorer = rouge_scorer.RougeScorer(['rouge1', 'rouge2', 'rougeL'], use_stemmer=True) | |
| rouge_scores = [scorer.score(ref, cand) for ref, cand in zip(references, candidates)] | |
| rouge1 = sum([score['rouge1'].fmeasure for score in rouge_scores]) / len(rouge_scores) | |
| return bleu_score, rouge1 | |
| def evaluate_bert_score(self, candidates, references): | |
| P, R, F1 = score(candidates, references, lang="en", model_type='bert-base-multilingual-cased') | |
| return P.mean().item(), R.mean().item(), F1.mean().item() | |
| def evaluate_perplexity(self, text): | |
| encodings = self.gpt2_tokenizer(text, return_tensors='pt') | |
| max_length = self.gpt2_model.config.n_positions | |
| stride = 512 | |
| lls = [] | |
| for i in range(0, encodings.input_ids.size(1), stride): | |
| begin_loc = max(i + stride - max_length, 0) | |
| end_loc = min(i + stride, encodings.input_ids.size(1)) | |
| trg_len = end_loc - i | |
| input_ids = encodings.input_ids[:, begin_loc:end_loc] | |
| target_ids = input_ids.clone() | |
| target_ids[:, :-trg_len] = -100 | |
| with torch.no_grad(): | |
| outputs = self.gpt2_model(input_ids, labels=target_ids) | |
| log_likelihood = outputs[0] * trg_len | |
| lls.append(log_likelihood) | |
| ppl = torch.exp(torch.stack(lls).sum() / end_loc) | |
| return ppl.item() | |
| def evaluate_diversity(self, texts): | |
| all_tokens = [tok for text in texts for tok in text.split()] | |
| unique_bigrams = set(ngrams(all_tokens, 2)) | |
| diversity_score = len(unique_bigrams) / len(all_tokens) if all_tokens else 0 | |
| return diversity_score | |
| def evaluate_racial_bias(self, text): | |
| results = self.bias_pipeline([text], candidate_labels=["hate speech", "not hate speech"]) | |
| bias_score = results[0]['scores'][results[0]['labels'].index('hate speech')] | |
| return bias_score | |
| def evaluate_all(self, response, reference): | |
| candidates = [response] | |
| references = [reference] | |
| bleu, rouge1 = self.evaluate_bleu_rouge(candidates, references) | |
| bert_p, bert_r, bert_f1 = self.evaluate_bert_score(candidates, references) | |
| perplexity = self.evaluate_perplexity(response) | |
| diversity = self.evaluate_diversity(candidates) | |
| racial_bias = self.evaluate_racial_bias(response) | |
| return { | |
| "BLEU": bleu, | |
| "ROUGE-1": rouge1, | |
| "BERT P": bert_p, | |
| "BERT R": bert_r, | |
| "BERT F1": bert_f1, | |
| "Perplexity": perplexity, | |
| "Diversity": diversity, | |
| "Racial Bias": racial_bias | |
| } | |