PT-M2

This repository contains the source code for "Revisiting Grammatical Error Correction Evaluation and Beyond", which experiments if recent pretrain-based (PT-based) metrics such as BERTScore and BARTScore are suitable for GEC evaluation task and proposes a novel PT-based GEC metric PT-M2, which uses to evaluate GEC system outputs with pretrained knowledge, measures whether the GEC system corrects more important errors.

Overview

PT-M2 takes advantages of both PT-based metrics (e.g. BERTScore, BARTScore) and edit-based metrics (e.g. M2, ERRANT). Without directly using PT-based metrics to score hypothesis-reference sentence pairs, we use them at the edit level to compute a score for each edit. Experiments show that PT-M2 correlates better with human judgements on both sentence-level and corpus-level, and is competent to evaluate high-performing GEC systems.

For an illustration, PT-M2 can be computed as

If you find this repo useful, please cite:

@inproceedings{gong2022revisiting,
 author = {Gong, Peiyuan and Liu, Xuebo and Huang, Heyan and Zhang, Min},
 booktitle = {Proceedings of the 2022 Conference on Empirical Methods in Natural Language Processing},
 title = {Revisiting Grammatical Error Correction Evaluation and Beyond},
 url = {https://arxiv.org/abs/2211.01635}, 
 year = {2022}
}

Installation

• Python version >= 3.6
• PyTorch version >= 1.0.0
• Transformers version >= 4.10.0
• errant >= 3.2.0

Install it from the source by:

git clone https://github.com/pygongnlp/PT-M2.git
cd PT-M2

Script

You can compute GEC system score based on this script, whether for M2, ERRANT or our PT-M2

python evaluate.py --base [m2|sentm2|errant|senterrant] \
                   --scorer [self|bertscore|bartscore] \
                   --model_type <model_type> \
                   --source <source_file> \
                   --hypothesis <hypothesis_file> \
                   --reference <reference_file> \
                   --output <output_file> 

where

OPTIONS
     --base    - GEC base metric, m2 or errant, corpus-level or sentence-level
     --scorer  - edit scorer, bertscore, bartscore or without scorer (self) 
     --model_type  - PT-based model, such as bert-base-uncased (bertscore)
     --beta    - F_beta, default = 0.5
     --source    - source file path
     --hypothesis    - hypothesis file path
     --reference    - reference file path
     --output    - output file path

We recommended PT-M2 configuration is base=sentm2, scorer=bertscore and model_type=bert-base-uncased

Example

We give an example (data/) to show how to compute PT-M2

Data preprocess

• Source, hypothesis, reference are used as inputs, multi reference files are supported. For example:

/PT-M2
  /data
      /reference
        ref0
        ref1 
      source
      hypothesis
      reference.m2 (m2score)

• For M2, exclude above three files, we also need a gold m2 file (reference.m2) annotated by human. (How to extract edits actually can be found in edit_creator)
• For ERRANT, we should extract source-hypothesis edits (m2_file) and source-references edits (m2_file) before compute the system score

# First we extract source-reference edits based on multi-references
errant_parallel -orig data/source -cor data/reference/ref0 data/reference/ref1 -out data/reference.m2
# Second we extracct source-hypothesis edits
errant_parallel -orig data/source -cor data/hypothesis -out data/hypothesis.m2

Compute score

python evaluate.py --source data/source --reference data/reference --hypothesis data/hypothesis --output data/output --base sentm2 --scorer bertscore --model_type bert-base-uncased

Results

base=sentm2, scorer=bertscore, model_type=bert-base-uncased, score=0.3756

Contact

If you have any questions related to the code or the paper, feel free to email Peiyuan Gong ([email protected]). If you encounter any problems when using the code, or want to report a bug, you can open an issue. Please try to specify the problem with details so we can help you better and quicker!