huggingface/transformers v0.5.0

Adding OpenAI GPT and Transformer-XL pretrained models, python2 support, pre-training script for BERT, SQuAD 2.0 example

on GitHub

New pretrained models:

• Open AI GPT pretrained on the Toronto Book Corpus ("Improving Language Understanding by Generative Pre-Training" by Alec Radford et al.).

  • This is a slightly modified version of our previous PyTorch implementation to increase the performances by spliting words and position embeddings in separate embeddings matrices.
  • Performance checked to be on part with the TF implementation on ROCStories: single run evaluation accuracy of 86.4% vs. authors reporting a median accuracy of 85.8% with the TensorFlow code (see details in the example section of the readme).

• Transformer-XL pretrained on WikiText 103 ("Transformer-XL: Attentive Language Models Beyond a Fixed-Length Context" by Zihang Dai, Zhilin Yang et al.). This is a slightly modified version of Google/CMU's PyTorch implementation to match the performances of the TensorFlow version by:

  • untying relative positioning embeddings across layers,
  • changing memory cells initialization to keep sinusoïdal positions identical
  • adding full logits outputs in the adaptive softmax to use it in a generative setting.
  • Performance checked to be on part with the TF implementation on WikiText 103: evaluation perplexity of 18.213 vs. authors reporting a perplexity of 18.3 on this dataset with the TensorFlow code (see details in the example section of the readme).

New scripts:

• Updated the SQuAD fine-tuning script to work also on SQuAD V2.0 by @abeljim and @Liangtaiwan
• run_lm_finetuning.py let you pretrain a BERT language model or fine-tune it with masked-language-modeling and next-sentence-prediction losses by @deepset-ai, @tholor and @nhatchan (compatibility Python 3.5)

Backward compatibility:

• The library is now compatible with Python 2 also

Improvements and bug fixes:

• add a never_split option and arguments to the tokenizers (@WrRan)
• better handle errors when BERT is feed with inputs that are too long (@patrick-s-h-lewis)
• better layer normalization layer initialization and bug fix in examples scripts: args.do_lower_case is always True(@donglixp)
• fix learning rate schedule issue in example scripts (@matej-svejda)
• readme fixes (@danyaljj, @nhatchan, @davidefiocco, @girishponkiya )
• importing unofficial TF models in BERT (@nhatchan)
• only keep the active part of the loss for token classification (@Iwontbecreative)
• fix argparse type error in example scripts (@ksurya)
• docstring fixes (@rodgzilla, @wlhgtc )
• improving run_classifier.py loading of saved models (@SinghJasdeep)
• In examples scripts: allow do_eval to be used without do_train and to use the pretrained model in the output folder (@jaderabbit, @likejazz and @JoeDumoulin )
• in run_squad.py: fix error when bert_model param is path or url (@likejazz)
• add license to source distribution and use entry-points instead of scripts (@sodre)