tokenizer

class FunnelTokenizer(vocab_file, do_lower_case=True, unk_token='<unk>', sep_token='<sep>', pad_token='<pad>', cls_token='<cls>', mask_token='<mask>', bos_token='<s>', eos_token='</s>', wordpieces_prefix='##', **kwargs)

Bases: paddlenlp.transformers.bert.tokenizer.BertTokenizer

property vocab_size

return the size of vocabulary. :returns: the size of vocabulary. :rtype: int

tokenize(text)

End-to-end tokenization for BERT models. :param text: The text to be tokenized. :type text: str

Returns

A list of string representing converted tokens.

Return type

list

convert_tokens_to_string(tokens)

Converts a sequence of tokens (list of string) in a single string. Since the usage of WordPiece introducing ## to concat subwords, also remove ## when converting. :param tokens: A list of string representing tokens to be converted. :type tokens: list

Returns

Converted string from tokens.

Return type

str

num_special_tokens_to_add(pair=False)

Returns the number of added tokens when encoding a sequence with special tokens.

Note

This encodes inputs and checks the number of added tokens, and is therefore not efficient. Do not put this inside your training loop.

Parameters

pair – Returns the number of added tokens in the case of a sequence pair if set to True, returns the number of added tokens in the case of a single sequence if set to False.

Returns

Number of tokens added to sequences

build_offset_mapping_with_special_tokens(offset_mapping_0, offset_mapping_1=None)

Build offset map from a pair of offset map by concatenating and adding offsets of special tokens.

A BERT offset_mapping has the following format:

- single sequence: ``(0,0) X (0,0)``
- pair of sequences: `(0,0) A (0,0) B (0,0)``

Parameters

• offset_mapping_ids_0 (List[tuple]) – List of char offsets to which the special tokens will be added.

• offset_mapping_ids_1 (List[tuple], optional) – Optional second list of char offsets for offset mapping pairs.

Returns

List of char offsets with the appropriate offsets of special tokens.

Return type

List[tuple]

create_token_type_ids_from_sequences(token_ids_0, token_ids_1=None)

Create a mask from the two sequences passed to be used in a sequence-pair classification task.

A BERT sequence pair mask has the following format:

0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1
| first sequence    | second sequence |

If token_ids_1 is None, this method only returns the first portion of the mask (0s).

Parameters

• token_ids_0 (List[int]) – A list of inputs_ids for the first sequence.

• token_ids_1 (List[int], optional) – Optional second list of IDs for sequence pairs. Defaults to None.

Returns

List of token_type_id according to the given sequence(s).

Return type

List[int]

get_special_tokens_mask(token_ids_0, token_ids_1=None, already_has_special_tokens=False)

Retrieves sequence ids from a token list that has no special tokens added. This method is called when adding special tokens using the tokenizer encode methods.

Parameters

• token_ids_0 (List[int]) – List of ids of the first sequence.

• token_ids_1 (List[int], optional) – List of ids of the second sequence.

• already_has_special_tokens (bool, optional) – Whether or not the token list is already formatted with special tokens for the model. Defaults to None.

Returns

The list of integers in the range [0, 1]: 1 for a special token, 0 for a sequence token.

Return type

results (List[int])

truncate_sequences(ids, pair_ids=None, num_tokens_to_remove=0, truncation_strategy='longest_first', stride=0)

Truncates a sequence pair in place to the maximum length.

Parameters

• ids – list of tokenized input ids. Can be obtained from a string by chaining the tokenize and convert_tokens_to_ids methods.

• pair_ids – Optional second list of input ids. Can be obtained from a string by chaining the tokenize and convert_tokens_to_ids methods.

• num_tokens_to_remove (int, optional, defaults to 0) – number of tokens to remove using the truncation strategy

• truncation_strategy –

  string selected in the following options: - ‘longest_first’ (default) Iteratively reduce the inputs sequence until the input is under max_seq_len

  starting from the longest one at each token (when there is a pair of input sequences). Overflowing tokens only contains overflow from the first sequence.

  • ’only_first’: Only truncate the first sequence. raise an error if the first sequence is shorter or equal to than num_tokens_to_remove.

  • ’only_second’: Only truncate the second sequence

  • ’do_not_truncate’: Does not truncate (raise an error if the input sequence is longer than max_seq_len)

• stride (int, optional, defaults to 0) – If set to a number along with max_seq_len, the overflowing tokens returned will contain some tokens from the main sequence returned. The value of this argument defines the number of additional tokens.

batch_encode(batch_text_or_text_pairs, max_seq_len=512, pad_to_max_seq_len=False, stride=0, is_split_into_words=False, truncation_strategy='longest_first', return_position_ids=False, return_token_type_ids=True, return_attention_mask=False, return_length=False, return_overflowing_tokens=False, return_special_tokens_mask=False)

Performs tokenization and uses the tokenized tokens to prepare model inputs. It supports batch inputs of sequence or sequence pair. :param batch_text_or_text_pairs: The element of list can be sequence or sequence pair, and the

sequence is a string or a list of strings depending on whether it has been pretokenized. If each sequence is provided as a list of strings (pretokenized), you must set is_split_into_words as True to disambiguate with a sequence pair.

Parameters

• max_seq_len (int, optional) – If set to a number, will limit the total sequence returned so that it has a maximum length. If there are overflowing tokens, those overflowing tokens will be added to the returned dictionary when return_overflowing_tokens is True. Defaults to None.

• stride (int, optional) – Only available for batch input of sequence pair and mainly for question answering usage. When for QA, text represents questions and text_pair represents contexts. If stride is set to a positive number, the context will be split into multiple spans where stride defines the number of (tokenized) tokens to skip from the start of one span to get the next span, thus will produce a bigger batch than inputs to include all spans. Moreover, ‘overflow_to_sample’ and ‘offset_mapping’ preserving the original example and position information will be added to the returned dictionary. Defaults to 0.

• pad_to_max_seq_len (bool, optional) – If set to True, the returned sequences would be padded up to max_seq_len specified length according to padding side (self.padding_side) and padding token id. Defaults to False.

• truncation_strategy (str, optional) – String selected in the following options: - ‘longest_first’ (default) Iteratively reduce the inputs sequence until the input is under max_seq_len starting from the longest one at each token (when there is a pair of input sequences). - ‘only_first’: Only truncate the first sequence. - ‘only_second’: Only truncate the second sequence. - ‘do_not_truncate’: Do not truncate (raise an error if the input sequence is longer than max_seq_len). Defaults to ‘longest_first’.

• return_position_ids (bool, optional) – Whether to include tokens position ids in the returned dictionary. Defaults to False.

• return_token_type_ids (bool, optional) – Whether to include token type ids in the returned dictionary. Defaults to True.

• return_attention_mask (bool, optional) – Whether to include the attention mask in the returned dictionary. Defaults to False.

• return_length (bool, optional) – Whether to include the length of each encoded inputs in the returned dictionary. Defaults to False.

• return_overflowing_tokens (bool, optional) – Whether to include overflowing token information in the returned dictionary. Defaults to False.

• return_special_tokens_mask (bool, optional) – Whether to include special tokens mask information in the returned dictionary. Defaults to False.

Returns

The dict has the following optional items: - input_ids (list[int]): List of token ids to be fed to a model. - position_ids (list[int], optional): List of token position ids to be

fed to a model. Included when return_position_ids is True

• token_type_ids (list[int], optional): List of token type ids to be fed to a model. Included when return_token_type_ids is True.

• attention_mask (list[int], optional): List of integers valued 0 or 1, where 0 specifies paddings and should not be attended to by the model. Included when return_attention_mask is True.

• seq_len (int, optional): The input_ids length. Included when return_length is True.

• overflowing_tokens (list[int], optional): List of overflowing tokens. Included when if max_seq_len is specified and return_overflowing_tokens is True.

• num_truncated_tokens (int, optional): The number of overflowing tokens. Included when if max_seq_len is specified and return_overflowing_tokens is True.

• special_tokens_mask (list[int], optional): List of integers valued 0 or 1, with 0 specifying special added tokens and 1 specifying sequence tokens. Included when return_special_tokens_mask is True.

• offset_mapping (list[int], optional): list of pair preserving the index of start and end char in original input for each token. For a sqecial token, the index pair is (0, 0). Included when stride works.

• overflow_to_sample (int, optional): Index of example from which this feature is generated. Included when stride works.

Return type

list[dict]

rematch(text)

changed from https://github.com/bojone/bert4keras/blob/master/bert4keras/tokenizers.py#L372