Attention-based Neural Machine Translation

Installation

The following packages are needed:

• Pytorch >= 0.4.0
• NLTK

Preparation

To obtain vocabulary for training, run:

python scripts/buildvocab.py --corpus /path/to/train.cn --output /path/to/cn.voc3.pkl \
--limit 30000 --groundhog
python scripts/buildvocab.py --corpus /path/to/train.en --output /path/to/en.voc3.pkl \
--limit 30000 --groundhog

Training

Training the RNNSearch on Chinese-English translation datasets as follows:

python train.py \
--src_vocab /path/to/cn.voc3.pkl --trg_vocab /path/to/en.voc3.pkl \
--train_src corpus/train.cn-en.cn --train_trg corpus/train.cn-en.en \
--valid_src corpus/nist02/nist02.cn \
--valid_trg corpus/nist02/nist02.en0 corpus/nist02/nist02.en1 corpus/nist02/nist02.en2 corpus/nist02/nist02.en3 \
--eval_script scripts/validate.sh \
--model RNNSearch \
--optim RMSprop \
--batch_size 80 \
--half_epoch \
--cuda \
--info RMSprop-half_epoch 

Evaluation

python translate.py \
--src_vocab /path/to/cn.voc3.pkl --trg_vocab /path/to/en.voc3.pkl \
--test_src corpus/nist03/nist03.cn \
--test_trg corpus/nist03/nist02.en0 corpus/nist03/nist03.en1 corpus/nist03/nist03.en2 corpus/nist03/nist03.en3 \
--eval_script scripts/validate.sh \
--model RNNSearch \
--name RNNSearch.best.pt \
--cuda 

The evaluation metric for Chinese-English we use is case-insensitive BLEU. We use the muti-bleu.perl script from Moses to compute the BLEU:

perl scripts/multi-bleu.perl -lc corpus/nist03/nist03.en < nist03.translated

Results on Chinese-English translation

The trainining dataset consists of 1.25M billingual sentence pairs extracted from LDC corpora. Use NIST 2002(MT02) as tuning set for hyper-parameter optimization and model selection, and NIST 2003(MT03), 2004 (MT04), 2005(MT05), 2006(MT06) and 2008(MT08) as test sets. The beam size is set to 10.

MT02	MT03	MT04	MT05	MT06	MT08	Ave.
40.16	37.26	40.50	36.67	37.10	28.54	36.01

Acknowledgements

My implementation utilizes code from the following:

• DeepLearnXMU's ABD-NMT repo