# PaddleNLP Metrics API

Currently, PaddleNLP provides the following model evaluation metrics:

| Metric | Description | API |
| ------ | ----------- | --- |
| [Perplexity](https://en.wikipedia.org/wiki/Perplexity)  | Perplexity, commonly used to evaluate the quality of language models, and applicable to tasks such as machine translation and text generation. | `paddlenlp.metrics.Perplexity`                               |
| [BLEU (BiLingual Evaluation Understudy)](https://en.wikipedia.org/wiki/BLEU)           | A commonly used evaluation metric for machine translation.          | `paddlenlp.metrics.BLEU`                                     |
| [Rouge (Recall-Oriented Understudy for Gisting Evaluation)](https://en.wikipedia.org/wiki/ROUGE_(metric)) | A metric for evaluating automatic summarization and machine translation.   | `paddlenlp.metrics.RougeL`, `paddlenlp.metrics.RougeN`       |
| AccuracyAndF1                                            | Accuracy and F1-score, applicable to MRPC and QQP tasks in GLUE.               | `paddlenlp.metrics.AccuracyAndF1`                            |
| PearsonAndSpearman                                       | Pearson correlation coefficient and Spearman's rank correlation coefficient, applicable to the STS-B task in GLUE.  | `paddlenlp.metrics.PearsonAndSpearman`                       |
| Mcc (Matthews correlation coefficient)                    | Matthews correlation coefficient, used to measure the classification performance of binary classification tasks. Applicable to the CoLA task in GLUE. | `paddlenlp.metrics.Mcc`                                      |
| ChunkEvaluator                                           | Computes precision, recall, and F1-score for chunk detection. Commonly used in sequence labeling tasks such as Named Entity Recognition (NER). | `paddlenlp.metrics.ChunkEvaluator`                           |
| Squad Evaluation                        | Evaluation metrics for SQuAD and DuReader-robust.                         | `paddlenlp.metrics.compute_predictions`, `paddlenlp.metrics.squad_evaluate`
| [Distinct](https://arxiv.org/abs/1510.03055) | A diversity metric commonly used to measure the form diversity of sentences generated by text generation models. | `paddlenlp.metrics.Distinct` |