Stance Classifier for the WeVerify project, to determine the stance (support, deny, question, comment) of a "reply" tweet or other social media post towards the original "target" post to which it is replying.

This is the latest version of the classifier, with target-aware and target-oblivious models based on BERTweet and XLM-RoBERTa. For the older multilingual BERT-based models see the bert-model branch

There are two versions of the stance classifier available:

• "target aware" - a mode that uses both the reply post and the target post together to determine the stance. This uses two models fine-tuned from vinai/bertweet-base, one for just the reply and one for the target and reply together
• "target oblivious" - a mode that uses just the reply post, without reference to the target. This model is fine tuned from cardiffnlp/twitter-xlm-roberta-base, which is a multilingual model, but the fine tuning data is still the RumourEval 2019 data set which is English only.

python -m StanceClassifier reply.json [original.json]

The reply and (if provided) original arguments should be JSON files containing tweets in JSON format with at least a "text" or "full_text" property containing the text. If only a reply is provided then the target-oblivious model will be used, if an original tweet is provided as well then the ensemble model will be used that combines a target-oblivious and a target-aware model and picks the best classification.

The output is a class:

• 0.0 = support
• 1.0 = deny
• 2.0 = query
• 3.0 = comment

and a vector with the probabilities returned for each class.

The folder examples contains examples of original tweets and replies:

• original_old and reply_old are examples of the old JSON files (140 characters)
• original_new and reply_new are examples of the new JSON files (280 characters)

The project provides three main classes, StanceClassifer for target-oblivious stance detection and StanceClassifierEnsemble for the target-aware ensemble model, plus StanceClassifierWithTarget that uses only the target-aware model. All these classes can be imported from StanceClassifier.stance_classifier, and will download their models from HuggingFace on first use.

The docker directory contains configuration to build a Docker image running a particular model of the classifier as an HTTP endpoint compliant with the API specification of the European Language Grid.

To train new models, you can edit train_model.py (more support will be given in the future). To run:

python train_model.py