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few-shot-text-classification

Few-shot binary text classification with Induction Networks and Word2Vec weights initialization

This is an PyTorch implementation of IJCNLP 2019 paper Induction Networks for Few-Shot Text Classification.

Few-shot classification is a task in which a classifier must be adapted to accommodate new classes not seen in training, given only a few examples of each of these new classes.
There is a large labeled training set with a set of classes. However, after training, the ultimate goal is to produce classifiers on the test set (a disjoint set of new classes), for which only a small labeled support set will be available.
If the support set contains K labeled examples for each of the C unique classes, the target few-shot problem is called C-way K-shot problem.
Usually, the K is too small to train a supervised classification model. Therefore meta-learning on the training set is necessary, in order to extract transferable knowledge that will help classify the test set more successfully.

pip install -r requirements.txt

The dataset comprises English reviews for 23 types of products on Amazon.
For each product domain, there are three different binary classification tasks. These buckets then form 23 x 3 = 69 tasks in total.
4 x 3 = 12 tasks from 4 test domains (Books, DVD, Electronics and Kitchen) are selected as test set, and there are only 5 examples as support set for each labels in the test set. There other 19 domains are train domains.

Train Tasks	Dev Tasks	Test Tasks
19 * 3 = 57	4 * 3 = 12	4 * 3 = 12

python data.py

Data for train, dev and test:
- Train data: *.train files in train domains.
- Dev data: *.trian files in test domains as support data and *.dev files in test domains as query data.
- Test data: *.trian files in test domains as support data and *.test files in test domains as query data.
Pre-process all the texts data.
Extract vocabulary with train data. Vocabulary has size of 35913, with 0 as <pad> and 1 as <unk>.
Index all the texts with the vocabulary.
Training batch composition: 5 negative support data + 5 positive support data + 27 negative query data + 27 positive query data. In each batch, support data and query data are randomly divided. As this is a 2-way 5-shot problem, the 2-ways means the amount of labels (negative/positive) and the 5-shot means the size of support data with the same label.
Dev batch composition: 5 negative support data + 5 positive support data + 54 query data. There are 183 batches in total.
Test batch composition: 5 negative support data + 5 positive support data + 54 query data. There are 181 batches in total.
Above all, the batch size is always 64.

python word2vec.py

It is hard to train without Word2Vec weights initialization! Therefore Word2Vec weights are necessary!
Train Word2Vec model with texts in train data, 95584 texts in total.
Get the weights of the Word2Vec model.
Load the weights in the encoder module.

Encoder Module: bi-direction recurrent neural network with self-attention.
Induction Module: dynamic routing induction algorithm.
Relation Module: measure the correlation between each pair of query and class and output the relation scores.
See the paper in the reference section (at the end) for details.

export CUDA_VISIBLE_DEVICES=1
python main.py

Training Strategy: episode-based meta training
Dev while training and record dev accuracy.
Pick the checkpoint with the highest dev accuracy as the best model and test on it.

tensorboard --logdir=log/

Train Loss	Train Accuracy

Dev Accuracy (achieves the highest 0.8410 at episode 9200)	Test Accuracy (at episode 9200)	Test Accuracy (paper)
	0.8452	0.8563

Zhongyu Chen