Swiss Language Model

A language model for Swiss German based on Huggingface/Transformers.

Using BERT: Pre-training of Deep Bidirectional Transformers for Language Understanding pre-trained on cased German text by Deepset.ai, which included: German Wikipedia dump (6GB of raw txt files), the OpenLegalData dump (2.4 GB) and news articles (3.6 GB)

The model is then fine tuned on the Swiss German data of the Leipzig Corpora Collection and SwissCrawl.

Alternatively, a GPT-2 model can also be trained, but there is no German pre-trained model available for that.

Requirements

• Python 3
• PyTorch
• Huggingface/Transformers

All dependencies can be installed with pip.

pip install --user -r requirements.txt

On Windows the PyTorch packages may not be available on PyPi, hence you need to point to the official PyTorch registry:

pip install --user -r requirements.txt -f https://download.pytorch.org/whl/torch_stable.html

If you'd like to use a different installation method or another CUDA version with PyTorch follow the instructions on PyTorch - Getting Started.

Models

Model	Configuration	Datasets used for training	Download
bert-swiss-lm	bert-base	Leipzig and SwissCrawl	Google Drive

Usage

Data

Data for training essentially raw text files, but since the Leipzig corpus uses a TSV style, that has been kept, but instead of the second column containing the sentences (first one in Leipzig corpus is the index), it is now the first one. This means you can add more columns after the first one, if you have a dataset that needs additional labels (e.g. for sentiment of the sentence) or just any additional information that will be ignored during training.

The Leipzig corpus can be converted with prepare_data.py:

python prepare_data.py -i data/leipzig.tsv -o leipzig-converted --split 80

-o/--output is the output directory for all the generated data. If not given, it will be generated to data/<basename-of-input-file>, which would be data/leipzig/ in this example. --split optionally generates a training validation split (80/20 in this case) additionally to the full data. You can also generate a vocabulary, SentencePiece, WordPiece (BERT's style) and Byte Pair Encoding (BPE) from the input by supplying the --vocab flag.

Similarly, the SwissCrawl data can be prepared by setting the -t/--type option to swiss-crawl. For this preparation a minimum probability of 0.99 is used by default and can be changed with -p/--p.

python prepare_data.py -i data/swiss-crawl.csv -o swiss-crawl-converted --split 80 -t swiss-crawl

Training

Training is done with the train.py script:

python train.py --name some-name -c log/some-name/checkpoints/0022/ --train-text /path/to/text.tsv --validation-text /path/to/text.tsv --fp16

The --name option is used to give it a name, otherwise the checkpoints are just numbered without any given name and -c is to resume from the given checkpoint, if not specified it starts fresh.

Modern GPUs contain Tensor Cores (starting from V100 and RTX series) which enable mixed precision calculation, using optimised fp16 operations while still keeping the fp32 weights and therefore precision.

It can be enabled by setting the --fp16 flag.

Other GPUs without Tensor Cores do not benefit from using mixed precision since they only do fp32 operations and you may find it even becoming slower.

Different models can be selected with the -m/--model option, which are either bert or gpt2, to fine tune a pre-trained model, which can be changed with the --pre-trained option by specifying one model available at Huggingface Transformers - Pretrained Models or by specifyiing a path to the pre-trained model. There's also the possibility to train either of the model from scratch by choosing bert-scratch or gpt-scratch for the --model. The configuration used can still be changed with the --pre-trained option, but the pre-trained weights will not be loaded, just the configuration. Addtionally, the vocabulary can be changed with --vocab (path to the directory of the generated vocabularies) if another vocbaulary instead of the pre-trained one should be used.

For all options see python train.py --help.

Logs

During the training various types of logs are created with Lavd and everything can be found in log/ and is grouped by the experiment name.

• Summary
• Checkpoints
• Top 5 Checkpoints
• TensorBoard
• Event logs

To visualise the logged data run:

lavd log/