.. Copyright 2020 The HuggingFace Team. All rights reserved. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. Multi-lingual models ======================================================================================================================= Most of the models available in this library are mono-lingual models (English, Chinese and German). A few multi-lingual models are available and have a different mechanisms than mono-lingual models. This page details the usage of these models. The two models that currently support multiple languages are BERT and XLM. XLM ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ XLM has a total of 10 different checkpoints, only one of which is mono-lingual. The 9 remaining model checkpoints can be split in two categories: the checkpoints that make use of language embeddings, and those that don't XLM & Language Embeddings ----------------------------------------------------------------------------------------------------------------------- This section concerns the following checkpoints: - ``xlm-mlm-ende-1024`` (Masked language modeling, English-German) - ``xlm-mlm-enfr-1024`` (Masked language modeling, English-French) - ``xlm-mlm-enro-1024`` (Masked language modeling, English-Romanian) - ``xlm-mlm-xnli15-1024`` (Masked language modeling, XNLI languages) - ``xlm-mlm-tlm-xnli15-1024`` (Masked language modeling + Translation, XNLI languages) - ``xlm-clm-enfr-1024`` (Causal language modeling, English-French) - ``xlm-clm-ende-1024`` (Causal language modeling, English-German) These checkpoints require language embeddings that will specify the language used at inference time. These language embeddings are represented as a tensor that is of the same shape as the input ids passed to the model. The values in these tensors depend on the language used and are identifiable using the ``lang2id`` and ``id2lang`` attributes from the tokenizer. Here is an example using the ``xlm-clm-enfr-1024`` checkpoint (Causal language modeling, English-French): .. code-block:: >>> import torch >>> from transformers import XLMTokenizer, XLMWithLMHeadModel >>> tokenizer = XLMTokenizer.from_pretrained("xlm-clm-enfr-1024") >>> model = XLMWithLMHeadModel.from_pretrained("xlm-clm-enfr-1024") The different languages this model/tokenizer handles, as well as the ids of these languages are visible using the ``lang2id`` attribute: .. code-block:: >>> print(tokenizer.lang2id) {'en': 0, 'fr': 1} These ids should be used when passing a language parameter during a model pass. Let's define our inputs: .. code-block:: >>> input_ids = torch.tensor([tokenizer.encode("Wikipedia was used to")]) # batch size of 1 We should now define the language embedding by using the previously defined language id. We want to create a tensor filled with the appropriate language ids, of the same size as input_ids. For english, the id is 0: .. code-block:: >>> language_id = tokenizer.lang2id['en'] # 0 >>> langs = torch.tensor([language_id] * input_ids.shape[1]) # torch.tensor([0, 0, 0, ..., 0]) >>> # We reshape it to be of size (batch_size, sequence_length) >>> langs = langs.view(1, -1) # is now of shape [1, sequence_length] (we have a batch size of 1) You can then feed it all as input to your model: .. code-block:: >>> outputs = model(input_ids, langs=langs) The example :prefix_link:`run_generation.py ` can generate text using the CLM checkpoints from XLM, using the language embeddings. XLM without Language Embeddings ----------------------------------------------------------------------------------------------------------------------- This section concerns the following checkpoints: - ``xlm-mlm-17-1280`` (Masked language modeling, 17 languages) - ``xlm-mlm-100-1280`` (Masked language modeling, 100 languages) These checkpoints do not require language embeddings at inference time. These models are used to have generic sentence representations, differently from previously-mentioned XLM checkpoints. BERT ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ BERT has two checkpoints that can be used for multi-lingual tasks: - ``bert-base-multilingual-uncased`` (Masked language modeling + Next sentence prediction, 102 languages) - ``bert-base-multilingual-cased`` (Masked language modeling + Next sentence prediction, 104 languages) These checkpoints do not require language embeddings at inference time. They should identify the language used in the context and infer accordingly. XLM-RoBERTa ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ XLM-RoBERTa was trained on 2.5TB of newly created clean CommonCrawl data in 100 languages. It provides strong gains over previously released multi-lingual models like mBERT or XLM on downstream tasks like classification, sequence labeling and question answering. Two XLM-RoBERTa checkpoints can be used for multi-lingual tasks: - ``xlm-roberta-base`` (Masked language modeling, 100 languages) - ``xlm-roberta-large`` (Masked language modeling, 100 languages)