Project: Fine-Tuning BERT for Text Classification (TensorFlow)
Objective:
Fine-tune a pre-trained BERT model for binary text classification (e.g., Quora insincere questions dataset) using TensorFlow and TensorFlow Hub.
Tasks:
-
Setup: Install TensorFlow and TensorFlow Model Garden.
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Data Preparation:
- Download and import the Quora Insincere Questions dataset.
- Split into train, validation, and test sets, addressing class imbalance.
- Create TensorFlow Datasets (
tf.data
) for efficient data loading and preprocessing.
-
BERT Model Preparation:
- Load a pre-trained BERT model from TensorFlow Hub.
- Tokenize and preprocess text data for BERT input (input word IDs, input mask, segment IDs).
- Wrap Python functions for preprocessing into TensorFlow operations using
tf.py_function
.
-
Model Building:
- Add a classification head (dense layer with sigmoid activation) to the BERT layer.
- Compile the model with Adam optimizer and binary cross-entropy loss.
-
Fine-tuning:
- Train the model on the training data for a few epochs, validating on the validation set.
- Use early stopping to prevent overfitting.
-
Evaluation:
- Plot training and validation loss/accuracy curves.
- Evaluate the best model on the test set.
Key Points:
- BERT is a powerful transformer-based model for NLP tasks.
- Fine-tuning allows adapting BERT to specific classification tasks.
- TensorFlow and TensorFlow Hub provide convenient tools for working with BERT.
- tf.data API enables efficient data input pipelines for training and evaluation.
Additional Notes:
- BERT's architecture consists of multiple transformer encoder blocks.
- It produces contextualized embeddings for each token in the input sequence.
- The [CLS] token is often used as the aggregated representation for classification.
Limitations:
- BERT can be computationally expensive to train and fine-tune.
- Requires significant labelled data for effective fine-tuning.