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# MarianMT

**Bugs:** If you see something strange, file a [Github Issue](https://github.com/huggingface/transformers/issues/new?assignees=sshleifer&labels=&template=bug-report.md&title)
and assign @patrickvonplaten.

Translations should be similar, but not identical to output in the test set linked to in each model card.

## Implementation Notes

- Each model is about 298 MB on disk, there are more than 1,000 models.
- The list of supported language pairs can be found [here](https://huggingface.co/Helsinki-NLP).
- Models were originally trained by [Jörg Tiedemann](https://researchportal.helsinki.fi/en/persons/j%C3%B6rg-tiedemann) using the [Marian](https://marian-nmt.github.io/) C++ library, which supports fast training and translation.
- All models are transformer encoder-decoders with 6 layers in each component. Each model's performance is documented
  in a model card.
- The 80 opus models that require BPE preprocessing are not supported.
- The modeling code is the same as [`BartForConditionalGeneration`] with a few minor modifications:

  - static (sinusoid) positional embeddings (`MarianConfig.static_position_embeddings=True`)
  - no layernorm_embedding (`MarianConfig.normalize_embedding=False`)
  - the model starts generating with `pad_token_id` (which has 0 as a token_embedding) as the prefix (Bart uses
    `<s/>`),
- Code to bulk convert models can be found in `convert_marian_to_pytorch.py`.
- This model was contributed by [sshleifer](https://huggingface.co/sshleifer).

## Naming

- All model names use the following format: `Helsinki-NLP/opus-mt-{src}-{tgt}`
- The language codes used to name models are inconsistent. Two digit codes can usually be found [here](https://developers.google.com/admin-sdk/directory/v1/languages), three digit codes require googling "language
  code {code}".
- Codes formatted like `es_AR` are usually `code_{region}`. That one is Spanish from Argentina.
- The models were converted in two stages. The first 1000 models use ISO-639-2 codes to identify languages, the second
  group use a combination of ISO-639-5 codes and ISO-639-2 codes.


## Examples

- Since Marian models are smaller than many other translation models available in the library, they can be useful for
  fine-tuning experiments and integration tests.
- [Fine-tune on GPU](https://github.com/huggingface/transformers/blob/master/examples/research_projects/seq2seq-distillation/train_distil_marian_enro_teacher.sh)
- [Fine-tune on GPU with pytorch-lightning](https://github.com/huggingface/transformers/blob/master/examples/research_projects/seq2seq-distillation/train_distil_marian_no_teacher.sh)

## Multilingual Models

- All model names use the following format: `Helsinki-NLP/opus-mt-{src}-{tgt}`:
- If a model can output multiple languages, and you should specify a language code by prepending the desired output
  language to the `src_text`.
- You can see a models's supported language codes in its model card, under target constituents, like in [opus-mt-en-roa](https://huggingface.co/Helsinki-NLP/opus-mt-en-roa).
- Note that if a model is only multilingual on the source side, like `Helsinki-NLP/opus-mt-roa-en`, no language
  codes are required.

New multi-lingual models from the [Tatoeba-Challenge repo](https://github.com/Helsinki-NLP/Tatoeba-Challenge)
require 3 character language codes:

```python
>>> from transformers import MarianMTModel, MarianTokenizer

>>> src_text = [
...     ">>fra<< this is a sentence in english that we want to translate to french",
...     ">>por<< This should go to portuguese",
...     ">>esp<< And this to Spanish",
... ]

>>> model_name = "Helsinki-NLP/opus-mt-en-roa"
>>> tokenizer = MarianTokenizer.from_pretrained(model_name)
>>> print(tokenizer.supported_language_codes)
['>>zlm_Latn<<', '>>mfe<<', '>>hat<<', '>>pap<<', '>>ast<<', '>>cat<<', '>>ind<<', '>>glg<<', '>>wln<<', '>>spa<<', '>>fra<<', '>>ron<<', '>>por<<', '>>ita<<', '>>oci<<', '>>arg<<', '>>min<<']

>>> model = MarianMTModel.from_pretrained(model_name)
>>> translated = model.generate(**tokenizer(src_text, return_tensors="pt", padding=True))
>>> [tokenizer.decode(t, skip_special_tokens=True) for t in translated]
["c'est une phrase en anglais que nous voulons traduire en français",
 'Isto deve ir para o português.',
 'Y esto al español']
```

Here is the code to see all available pretrained models on the hub:

```python
from huggingface_hub import list_models

model_list = list_models()
org = "Helsinki-NLP"
model_ids = [x.modelId for x in model_list if x.modelId.startswith(org)]
suffix = [x.split("/")[1] for x in model_ids]
old_style_multi_models = [f"{org}/{s}" for s in suffix if s != s.lower()]
```

## Old Style Multi-Lingual Models

These are the old style multi-lingual models ported from the OPUS-MT-Train repo: and the members of each language
group:

```python no-style
['Helsinki-NLP/opus-mt-NORTH_EU-NORTH_EU',
 'Helsinki-NLP/opus-mt-ROMANCE-en',
 'Helsinki-NLP/opus-mt-SCANDINAVIA-SCANDINAVIA',
 'Helsinki-NLP/opus-mt-de-ZH',
 'Helsinki-NLP/opus-mt-en-CELTIC',
 'Helsinki-NLP/opus-mt-en-ROMANCE',
 'Helsinki-NLP/opus-mt-es-NORWAY',
 'Helsinki-NLP/opus-mt-fi-NORWAY',
 'Helsinki-NLP/opus-mt-fi-ZH',
 'Helsinki-NLP/opus-mt-fi_nb_no_nn_ru_sv_en-SAMI',
 'Helsinki-NLP/opus-mt-sv-NORWAY',
 'Helsinki-NLP/opus-mt-sv-ZH']
GROUP_MEMBERS = {
 'ZH': ['cmn', 'cn', 'yue', 'ze_zh', 'zh_cn', 'zh_CN', 'zh_HK', 'zh_tw', 'zh_TW', 'zh_yue', 'zhs', 'zht', 'zh'],
 'ROMANCE': ['fr', 'fr_BE', 'fr_CA', 'fr_FR', 'wa', 'frp', 'oc', 'ca', 'rm', 'lld', 'fur', 'lij', 'lmo', 'es', 'es_AR', 'es_CL', 'es_CO', 'es_CR', 'es_DO', 'es_EC', 'es_ES', 'es_GT', 'es_HN', 'es_MX', 'es_NI', 'es_PA', 'es_PE', 'es_PR', 'es_SV', 'es_UY', 'es_VE', 'pt', 'pt_br', 'pt_BR', 'pt_PT', 'gl', 'lad', 'an', 'mwl', 'it', 'it_IT', 'co', 'nap', 'scn', 'vec', 'sc', 'ro', 'la'],
 'NORTH_EU': ['de', 'nl', 'fy', 'af', 'da', 'fo', 'is', 'no', 'nb', 'nn', 'sv'],
 'SCANDINAVIA': ['da', 'fo', 'is', 'no', 'nb', 'nn', 'sv'],
 'SAMI': ['se', 'sma', 'smj', 'smn', 'sms'],
 'NORWAY': ['nb_NO', 'nb', 'nn_NO', 'nn', 'nog', 'no_nb', 'no'],
 'CELTIC': ['ga', 'cy', 'br', 'gd', 'kw', 'gv']
}
```

Example of translating english to many romance languages, using old-style 2 character language codes


```python
>>> from transformers import MarianMTModel, MarianTokenizer

>>> src_text = [
...     ">>fr<< this is a sentence in english that we want to translate to french",
...     ">>pt<< This should go to portuguese",
...     ">>es<< And this to Spanish",
... ]

>>> model_name = "Helsinki-NLP/opus-mt-en-ROMANCE"
>>> tokenizer = MarianTokenizer.from_pretrained(model_name)

>>> model = MarianMTModel.from_pretrained(model_name)
>>> translated = model.generate(**tokenizer(src_text, return_tensors="pt", padding=True))
>>> tgt_text = [tokenizer.decode(t, skip_special_tokens=True) for t in translated]
["c'est une phrase en anglais que nous voulons traduire en français", 
 'Isto deve ir para o português.',
 'Y esto al español']
```

## MarianConfig

[[autodoc]] MarianConfig

## MarianTokenizer

[[autodoc]] MarianTokenizer
    - as_target_tokenizer

## MarianModel

[[autodoc]] MarianModel
    - forward

## MarianMTModel

[[autodoc]] MarianMTModel
    - forward

## MarianForCausalLM

[[autodoc]] MarianForCausalLM
    - forward

## TFMarianModel

[[autodoc]] TFMarianModel
    - call

## TFMarianMTModel

[[autodoc]] TFMarianMTModel
    - call

## FlaxMarianModel

[[autodoc]] FlaxMarianModel
    - __call__

## FlaxMarianMTModel

[[autodoc]] FlaxMarianMTModel
    - __call__
