DL Translate

A deep learning-based translation library built on Huggingface transformers and Facebook's mBART-Large

💻 GitHub Repository
📚 Documentation / Readthedocs
🐍 PyPi project
🧪 Colab Demo / Kaggle Demo

Quickstart

Install the library with pip:

pip install dl-translate

To translate some text:

import dl_translate as dlt

mt = dlt.TranslationModel()  # Slow when you load it for the first time

text_hi = "संयुक्त राष्ट्र के प्रमुख का कहना है कि सीरिया में कोई सैन्य समाधान नहीं है"
mt.translate(text_hi, source=dlt.lang.HINDI, target=dlt.lang.ENGLISH)

Above, you can see that dlt.lang contains variables representing each of the 50 available languages with auto-complete support. Alternatively, you can specify the language (e.g. "Arabic") or the language code (e.g. "fr_XX" for French):

text_ar = "الأمين العام للأمم المتحدة يقول إنه لا يوجد حل عسكري في سوريا."
mt.translate(text_ar, source="Arabic", target="fr_XX")

If you want to verify whether a language is available, you can check it:

print(mt.available_languages())  # All languages that you can use
print(mt.available_codes())  # Code corresponding to each language accepted
print(mt.get_lang_code_map())  # Dictionary of lang -> code

Usage

Selecting a device

When you load the model, you can specify the device:

mt = dlt.TranslationModel(device="auto")

By default, the value will be device="auto", which means it will use a GPU if possible. You can also explicitly set device="cpu" or device="gpu", or some other strings accepted by torch.device(). In general, it is recommend to use a GPU if you want a reasonable processing time.

Loading from a path

By default, dlt.TranslationModel will download the model from the huggingface repo and cache it. However, you are free to load from a path:

mt = dlt.TranslationModel("/path/to/your/model/directory/")

Make sure that your tokenizer is also stored in the same directory if you use this approach.

Using a different model

You can also choose another model that has a similar format, e.g.

mt = dlt.TranslationModel("facebook/mbart-large-50-one-to-many-mmt")

Note that the available languages will change if you do this, so you will not be able to leverage dlt.lang or dlt.utils.

Breaking down into sentences

It is not recommended to use extremely long texts as it takes more time to process. Instead, you can try to break them down into sentences with the help of nltk. First install the library with pip install nltk, then run:

import nltk

nltk.download("punkt")

text = "Mr. Smith went to his favorite cafe. There, he met his friend Dr. Doe."
sents = nltk.tokenize.sent_tokenize(text, "english")  # don't use dlt.lang.ENGLISH
" ".join(mt.translate(sents, source=dlt.lang.ENGLISH, target=dlt.lang.FRENCH))

Batch size and verbosity when using translate

It's possible to set a batch size (i.e. the number of elements processed at once) for mt.translate and whether you want to see the progress bar or not:

...
mt = dlt.TranslationModel()
mt.translate(text, source, target, batch_size=32, verbose=True)

If you set batch_size=None, it will compute the entire text at once rather than splitting into "chunks". We recommend lowering batch_size if you do not have a lot of RAM or VRAM and run into CUDA memory error. Set a higher value if you are using a high-end GPU and the VRAM is not fully utilized.

dlt.utils module

An alternative to mt.available_languages() is the dlt.utils module. You can use it to find out which languages and codes are available:

print(dlt.utils.available_languages('mbart50'))  # All languages that you can use
print(dlt.utils.available_codes('mbart50'))  # Code corresponding to each language accepted
print(dlt.utils.get_lang_code_map('mbart50'))  # Dictionary of lang -> code

Advanced

The following section assumes you have knowledge of PyTorch and Huggingface Transformers.

Saving and loading

If you wish to accelerate the loading time the translation model, you can use save_obj:

mt = dlt.TranslationModel()
mt.save_obj('saved_model')
# ...

Then later you can reload it with load_obj:

mt = dlt.TranslationModel.load_obj('saved_model')
# ...

Warning: Only use this if you are certain the torch module saved in saved_model/weights.pt can be correctly loaded. Indeed, it is possible that the huggingface, torch or some other dependencies change between when you called save_obj and load_obj, and that might break your code. Thus, it is recommend to only run load_obj in the same environment/session as save_obj. Note this method might be deprecated in the future once there's no speed benefit in loading this way.

Interacting with underlying model and tokenizer

When initializing model, you can pass in arguments for the underlying BART model and tokenizer (which will respectively be passed to MBartForConditionalGeneration.from_pretrained and MBart50TokenizerFast.from_pretrained):

mt = dlt.TranslationModel(
    model_options=dict(
        state_dict=...,
        cache_dir=...,
        ...
    ),
    tokenizer_options=dict(
        tokenizer_file=...,
        eos_token=...,
        ...
    )
)

You can also access the underlying transformers model and tokenizer:

bart = mt.get_transformers_model()
tokenizer = mt.get_tokenizer()

See the huggingface docs for more information.

bart_model.generate() keyword arguments

When running mt.translate, you can also give a generation_options dictionary that is passed as keyword arguments to the underlying bart_model.generate() method:

mt.translate(
    text,
    source=dlt.lang.GERMAN,
    target=dlt.lang.SPANISH,
    generation_options=dict(num_beams=5, max_length=...)
)

Learn more in the huggingface docs.

Acknowledgement

dl-translate is built on top of Huggingface's implementation of multilingual BART finetuned on many-to-many translation of over 50 languages, which is documented here. The original paper was written by Tang et. al from Facebook AI Research; you can find it here and cite it using the following:

@article{tang2020multilingual,
  title={Multilingual translation with extensible multilingual pretraining and finetuning},
  author={Tang, Yuqing and Tran, Chau and Li, Xian and Chen, Peng-Jen and Goyal, Naman and Chaudhary, Vishrav and Gu, Jiatao and Fan, Angela},
  journal={arXiv preprint arXiv:2008.00401},
  year={2020}
}

dlt is a wrapper with useful utils to save you time. For huggingface's transformers, the following snippet is shown as an example:

from transformers import MBartForConditionalGeneration, MBart50TokenizerFast

article_hi = "संयुक्त राष्ट्र के प्रमुख का कहना है कि सीरिया में कोई सैन्य समाधान नहीं है"
article_ar = "الأمين العام للأمم المتحدة يقول إنه لا يوجد حل عسكري في سوريا."

model = MBartForConditionalGeneration.from_pretrained("facebook/mbart-large-50-many-to-many-mmt")
tokenizer = MBart50TokenizerFast.from_pretrained("facebook/mbart-large-50-many-to-many-mmt")

# translate Hindi to French
tokenizer.src_lang = "hi_IN"
encoded_hi = tokenizer(article_hi, return_tensors="pt")
generated_tokens = model.generate(**encoded_hi, forced_bos_token_id=tokenizer.lang_code_to_id["fr_XX"])
tokenizer.batch_decode(generated_tokens, skip_special_tokens=True)
# => "Le chef de l 'ONU affirme qu 'il n 'y a pas de solution militaire en Syria."

# translate Arabic to English
tokenizer.src_lang = "ar_AR"
encoded_ar = tokenizer(article_ar, return_tensors="pt")
generated_tokens = model.generate(**encoded_ar, forced_bos_token_id=tokenizer.lang_code_to_id["en_XX"])
tokenizer.batch_decode(generated_tokens, skip_special_tokens=True)
# => "The Secretary-General of the United Nations says there is no military solution in Syria."

With dlt, you can run:

import dl_translate as dlt

article_hi = "संयुक्त राष्ट्र के प्रमुख का कहना है कि सीरिया में कोई सैन्य समाधान नहीं है"
article_ar = "الأمين العام للأمم المتحدة يقول إنه لا يوجد حل عسكري في سوريا."

mt = dlt.TranslationModel()
translated_fr = mt.translate(article_hi, source=dlt.lang.HINDI, target=dlt.lang.FRENCH)
translated_en = mt.translate(article_ar, source=dlt.lang.ARABIC, target=dlt.lang.ENGLISH)

Notice you don't have to think about tokenizers, condition generation, pretrained models, and regional codes; you can just tell the model what to translate!

If you are experienced with huggingface's ecosystem, then you should be familiar enough with the example above that you wouldn't need this library. However, if you've never heard of huggingface or mBART, then I hope using this library will give you enough motivation to learn more about them :)