BERT_multilabel_text_classification

This project demonstrates how to make useof BERT enoder to train a multi label text classification problem. I have used the popular toxic comment classsifcation dataset from Kaggle. This project makes use of Bert-as-a-service project.

Requirements

1. Python >= 3.5
2. TensorFlow >= 1.10
3. Keras
4. bert-serving-server and bert-serving-client

steps

1. Install bert-serving-server and bert-serving-client using the below commands

pip install bert-serving-server 
pip install bert-serving-client

2. Download the bert base uncased model from here or using the below command

wget https://storage.googleapis.com/bert_models/2018_10_18/uncased_L-12_H-768_A-12.zip && unzip uncased_L-12_H-768_A-12.zip

3. Start the bert-serving-server

bert-serving-start -model_dir uncased_L-12_H-768_A-12/ -num_worker=2 -max_seq_len 50

Note: If you pass the max_seq_len parameter as None, the service will find the max length from each batch of text and use it for padding/truncating

4. Download the toxic text classification dataset from kaggle

5. Run the training script

python train.py

bert-serving-client objcet will bind to the server and encode the list of text which is being passed, into a (n, 768) dimension vector. Here n is the number of input sentences.

On top of this encoded vector we add a couple of dense layers to get the prediction.

Loss function and accuracy metric

I have used sigmoid + focal loss as loss function instead of usual sigmoid + binary crross entropy to tackle the class imbalnce problem in multi label predictions Also, instead of simple accuracy, AUCis being used.

Result

Result will be updated soon.

References

1. Google's Bert project
2. Bert as a service
3. Toxic comment challenge