``BertTokenizer`` perform end-to-end tokenization, i.e. basic tokenization followed by WordPiece tokenization.
This class has five arguments:
* ``vocab_file``\ : path to a vocabulary file.
* ``do_lower_case``\ : convert text to lower-case while tokenizing. **Default = True**.
* ``max_len``\ : max length to filter the input of the Transformer. Default to pre-trained value for the model if ``None``. **Default = None**
* ``do_basic_tokenize``\ : Do basic tokenization before wordpice tokenization. Set to false if text is pre-tokenized. **Default = True**.
* ``never_split``\ : a list of tokens that should not be splitted during tokenization. **Default = ``["[UNK]", "[SEP]", "[PAD]", "[CLS]", "[MASK]"]``\ **
and three methods:
.. autoclass:: pytorch_pretrained_bert.BertConfig
:members:
* ``tokenize(text)``\ : convert a ``str`` in a list of ``str`` tokens by (1) performing basic tokenization and (2) WordPiece tokenization.
* ``convert_tokens_to_ids(tokens)``\ : convert a list of ``str`` tokens in a list of ``int`` indices in the vocabulary.
* ``convert_ids_to_tokens(tokens)``\ : convert a list of ``int`` indices in a list of ``str`` tokens in the vocabulary.
* `save_vocabulary(directory_path)`: save the vocabulary file to `directory_path`. Return the path to the saved vocabulary file: ``vocab_file_path``. The vocabulary can be reloaded with ``BertTokenizer.from_pretrained('vocab_file_path')`` or ``BertTokenizer.from_pretrained('directory_path')``.
``BertTokenizer``
~~~~~~~~~~~~~~~~~~~~~
Please refer to the doc strings and code in `\ ``tokenization.py`` <./pytorch_pretrained_bert/tokenization.py>`_ for the details of the ``BasicTokenizer`` and ``WordpieceTokenizer`` classes. In general it is recommended to use ``BertTokenizer`` unless you know what you are doing.
``BertAdam`` is a ``torch.optimizer`` adapted to be closer to the optimizer used in the TensorFlow implementation of Bert. The differences with PyTorch Adam optimizer are the following:
* BertAdam implements weight decay fix,
* BertAdam doesn't compensate for bias as in the regular Adam optimizer.
The optimizer accepts the following arguments:
* ``lr`` : learning rate
* ``warmup`` : portion of ``t_total`` for the warmup, ``-1`` means no warmup. Default : ``-1``
* ``t_total`` : total number of training steps for the learning
rate schedule, ``-1`` means constant learning rate. Default : ``-1``
* ``schedule`` : schedule to use for the warmup (see above).
Can be ``'warmup_linear'``\ , ``'warmup_constant'``\ , ``'warmup_cosine'``\ , ``'none'``\ , ``None`` or a ``_LRSchedule`` object (see below).
If ``None`` or ``'none'``\ , learning rate is always kept constant.
* ``merges_file``\ : path to a file containing the BPE merges.
* ``max_len``\ : max length to filter the input of the Transformer. Default to pre-trained value for the model if ``None``. **Default = None**
* ``special_tokens``\ : a list of tokens to add to the vocabulary for fine-tuning. If SpaCy is not installed and BERT's ``BasicTokenizer`` is used as the pre-BPE tokenizer, these tokens are not split. **Default= None**
* ``tokenize(text)``\ : convert a ``str`` in a list of ``str`` tokens by performing BPE tokenization.
* ``convert_tokens_to_ids(tokens)``\ : convert a list of ``str`` tokens in a list of ``int`` indices in the vocabulary.
* ``convert_ids_to_tokens(tokens)``\ : convert a list of ``int`` indices in a list of ``str`` tokens in the vocabulary.
* ``set_special_tokens(self, special_tokens)``\ : update the list of special tokens (see above arguments)
* ``encode(text)``\ : convert a ``str`` in a list of ``int`` tokens by performing BPE encoding.
* `decode(ids, skip_special_tokens=False, clean_up_tokenization_spaces=False)`: decode a list of `int` indices in a string and do some post-processing if needed: (i) remove special tokens from the output and (ii) clean up tokenization spaces.
* `save_vocabulary(directory_path)`: save the vocabulary, merge and special tokens files to `directory_path`. Return the path to the three files: ``vocab_file_path``\ , ``merge_file_path``\ , ``special_tokens_file_path``. The vocabulary can be reloaded with ``OpenAIGPTTokenizer.from_pretrained('directory_path')``.
``OpenAIGPTTokenizer``
~~~~~~~~~~~~~~~~~~~~~~~~~~
Please refer to the doc strings and code in `\ ``tokenization_openai.py`` <./pytorch_pretrained_bert/tokenization_openai.py>`_ for the details of the ``OpenAIGPTTokenizer``.
* ``merges_file``\ : path to a file containing the BPE merges.
* ``errors``\ : How to handle unicode decoding errors. **Default = ``replace``\ **
and two methods:
.. autoclass:: pytorch_pretrained_bert.GPT2Config
:members:
* ``tokenize(text)``\ : convert a ``str`` in a list of ``str`` tokens by performing byte-level BPE.
* ``convert_tokens_to_ids(tokens)``\ : convert a list of ``str`` tokens in a list of ``int`` indices in the vocabulary.
* ``convert_ids_to_tokens(tokens)``\ : convert a list of ``int`` indices in a list of ``str`` tokens in the vocabulary.
* ``set_special_tokens(self, special_tokens)``\ : update the list of special tokens (see above arguments)
* ``encode(text)``\ : convert a ``str`` in a list of ``int`` tokens by performing byte-level BPE.
* ``decode(tokens)``\ : convert back a list of ``int`` tokens in a ``str``.
* `save_vocabulary(directory_path)`: save the vocabulary, merge and special tokens files to `directory_path`. Return the path to the three files: ``vocab_file_path``\ , ``merge_file_path``\ , ``special_tokens_file_path``. The vocabulary can be reloaded with ``OpenAIGPTTokenizer.from_pretrained('directory_path')``.
``GPT2Tokenizer``
~~~~~~~~~~~~~~~~~~~~~
Please refer to `\ ``tokenization_gpt2.py`` <./pytorch_pretrained_bert/tokenization_gpt2.py>`_ for more details on the ``GPT2Tokenizer``.
``TransfoXLTokenizer`` perform word tokenization. This tokenizer can be used for adaptive softmax and has utilities for counting tokens in a corpus to create a vocabulary ordered by toekn frequency (for adaptive softmax). See the adaptive softmax paper (\ `Efficient softmax approximation for GPUs <http://arxiv.org/abs/1609.04309>`_\ ) for more details.
The API is similar to the API of ``BertTokenizer`` (see above).
Please refer to the doc strings and code in `\ ``tokenization_transfo_xl.py`` <./pytorch_pretrained_bert/tokenization_transfo_xl.py>`_ for the details of these additional methods in ``TransfoXLTokenizer``.
