# 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.
import random
import warnings
from collections.abc import Mapping
from dataclasses import dataclass
from random import randint
from typing import Any, Callable, Dict, List, NewType, Optional, Tuple, Union
import numpy as np
from ..models.bert import BertTokenizer, BertTokenizerFast
from ..tokenization_utils_base import PreTrainedTokenizerBase
from ..utils import PaddingStrategy
InputDataClass = NewType("InputDataClass", Any)
"""
A DataCollator is a function that takes a list of samples from a Dataset and collate them into a batch, as a dictionary
of PyTorch/TensorFlow tensors or NumPy arrays.
"""
DataCollator = NewType("DataCollator", Callable[[List[InputDataClass]], Dict[str, Any]])
class DataCollatorMixin:
def __call__(self, features, return_tensors=None):
if return_tensors is None:
return_tensors = self.return_tensors
if return_tensors == "tf":
return self.tf_call(features)
elif return_tensors == "pt":
return self.torch_call(features)
elif return_tensors == "np":
return self.numpy_call(features)
else:
raise ValueError(f"Framework '{return_tensors}' not recognized!")
def pad_without_fast_tokenizer_warning(tokenizer, *pad_args, **pad_kwargs):
"""
Pads without triggering the warning about how using the pad function is sub-optimal when using a fast tokenizer.
"""
# To avoid errors when using Feature extractors
if not hasattr(tokenizer, "deprecation_warnings"):
return tokenizer.pad(*pad_args, **pad_kwargs)
# Save the state of the warning, then disable it
warning_state = tokenizer.deprecation_warnings.get("Asking-to-pad-a-fast-tokenizer", False)
tokenizer.deprecation_warnings["Asking-to-pad-a-fast-tokenizer"] = True
try:
padded = tokenizer.pad(*pad_args, **pad_kwargs)
finally:
# Restore the state of the warning.
tokenizer.deprecation_warnings["Asking-to-pad-a-fast-tokenizer"] = warning_state
return padded
def default_data_collator(features: List[InputDataClass], return_tensors="pt") -> Dict[str, Any]:
"""
Very simple data collator that simply collates batches of dict-like objects and performs special handling for
potential keys named:
- `label`: handles a single value (int or float) per object
- `label_ids`: handles a list of values per object
Does not do any additional preprocessing: property names of the input object will be used as corresponding inputs
to the model. See glue and ner for example of how it's useful.
"""
# In this function we'll make the assumption that all `features` in the batch
# have the same attributes.
# So we will look at the first element as a proxy for what attributes exist
# on the whole batch.
if return_tensors == "pt":
return torch_default_data_collator(features)
elif return_tensors == "tf":
return tf_default_data_collator(features)
elif return_tensors == "np":
return numpy_default_data_collator(features)
@dataclass
class DefaultDataCollator(DataCollatorMixin):
"""
Very simple data collator that simply collates batches of dict-like objects and performs special handling for
potential keys named:
- `label`: handles a single value (int or float) per object
- `label_ids`: handles a list of values per object
Does not do any additional preprocessing: property names of the input object will be used as corresponding inputs
to the model. See glue and ner for example of how it's useful.
This is an object (like other data collators) rather than a pure function like default_data_collator. This can be
helpful if you need to set a return_tensors value at initialization.
Args:
return_tensors (`str`, *optional*, defaults to `"pt"`):
The type of Tensor to return. Allowable values are "np", "pt" and "tf".
"""
return_tensors: str = "pt"
def __call__(self, features: List[Dict[str, Any]], return_tensors=None) -> Dict[str, Any]:
if return_tensors is None:
return_tensors = self.return_tensors
return default_data_collator(features, return_tensors)
def torch_default_data_collator(features: List[InputDataClass]) -> Dict[str, Any]:
import torch
if not isinstance(features[0], Mapping):
features = [vars(f) for f in features]
first = features[0]
batch = {}
# Special handling for labels.
# Ensure that tensor is created with the correct type
# (it should be automatically the case, but let's make sure of it.)
if "label" in first and first["label"] is not None:
label = first["label"].item() if isinstance(first["label"], torch.Tensor) else first["label"]
dtype = torch.long if isinstance(label, int) else torch.float
batch["labels"] = torch.tensor([f["label"] for f in features], dtype=dtype)
elif "label_ids" in first and first["label_ids"] is not None:
if isinstance(first["label_ids"], torch.Tensor):
batch["labels"] = torch.stack([f["label_ids"] for f in features])
else:
dtype = torch.long if isinstance(first["label_ids"][0], int) else torch.float
batch["labels"] = torch.tensor([f["label_ids"] for f in features], dtype=dtype)
# Handling of all other possible keys.
# Again, we will use the first element to figure out which key/values are not None for this model.
for k, v in first.items():
if k not in ("label", "label_ids") and v is not None and not isinstance(v, str):
if isinstance(v, torch.Tensor):
batch[k] = torch.stack([f[k] for f in features])
elif isinstance(v, np.ndarray):
batch[k] = torch.from_numpy(np.stack([f[k] for f in features]))
else:
batch[k] = torch.tensor([f[k] for f in features])
return batch
def tf_default_data_collator(features: List[InputDataClass]) -> Dict[str, Any]:
import tensorflow as tf
if not isinstance(features[0], Mapping):
features = [vars(f) for f in features]
first = features[0]
batch = {}
# Special handling for labels.
# Ensure that tensor is created with the correct type
# (it should be automatically the case, but let's make sure of it.)
if "label" in first and first["label"] is not None:
label_col_name = "label"
elif "label_ids" in first and first["label_ids"] is not None:
label_col_name = "label_ids"
elif "labels" in first and first["labels"] is not None:
label_col_name = "labels"
else:
label_col_name = None
if label_col_name is not None:
if isinstance(first[label_col_name], tf.Tensor):
dtype = tf.int64 if first[label_col_name].dtype.is_integer else tf.float32
elif isinstance(first[label_col_name], np.ndarray) or isinstance(first[label_col_name], np.generic):
dtype = tf.int64 if np.issubdtype(first[label_col_name].dtype, np.integer) else tf.float32
elif isinstance(first[label_col_name], (tuple, list)):
dtype = tf.int64 if isinstance(first[label_col_name][0], int) else tf.float32
else:
dtype = tf.int64 if isinstance(first[label_col_name], int) else tf.float32
batch["labels"] = tf.convert_to_tensor([f[label_col_name] for f in features], dtype=dtype)
# Handling of all other possible keys.
# Again, we will use the first element to figure out which key/values are not None for this model.
for k, v in first.items():
if k not in ("label", "label_ids", "labels") and v is not None and not isinstance(v, str):
if isinstance(v, (tf.Tensor, np.ndarray)):
batch[k] = tf.stack([f[k] for f in features])
else:
batch[k] = tf.convert_to_tensor([f[k] for f in features])
return batch
def numpy_default_data_collator(features: List[InputDataClass]) -> Dict[str, Any]:
if not isinstance(features[0], Mapping):
features = [vars(f) for f in features]
first = features[0]
batch = {}
# Special handling for labels.
# Ensure that tensor is created with the correct type
# (it should be automatically the case, but let's make sure of it.)
if "label" in first and first["label"] is not None:
label = first["label"].item() if isinstance(first["label"], np.ndarray) else first["label"]
dtype = np.int64 if isinstance(label, int) else np.float32
batch["labels"] = np.array([f["label"] for f in features], dtype=dtype)
elif "label_ids" in first and first["label_ids"] is not None:
if isinstance(first["label_ids"], np.ndarray):
batch["labels"] = np.stack([f["label_ids"] for f in features])
else:
dtype = np.int64 if isinstance(first["label_ids"][0], int) else np.float32
batch["labels"] = np.array([f["label_ids"] for f in features], dtype=dtype)
# Handling of all other possible keys.
# Again, we will use the first element to figure out which key/values are not None for this model.
for k, v in first.items():
if k not in ("label", "label_ids") and v is not None and not isinstance(v, str):
if isinstance(v, np.ndarray):
batch[k] = np.stack([f[k] for f in features])
else:
batch[k] = np.array([f[k] for f in features])
return batch
@dataclass
class DataCollatorWithPadding:
"""
Data collator that will dynamically pad the inputs received.
Args:
tokenizer ([`PreTrainedTokenizer`] or [`PreTrainedTokenizerFast`]):
The tokenizer used for encoding the data.
padding (`bool`, `str` or [`~utils.PaddingStrategy`], *optional*, defaults to `True`):
Select a strategy to pad the returned sequences (according to the model's padding side and padding index)
among:
- `True` or `'longest'` (default): Pad to the longest sequence in the batch (or no padding if only a single
sequence is provided).
- `'max_length'`: Pad to a maximum length specified with the argument `max_length` or to the maximum
acceptable input length for the model if that argument is not provided.
- `False` or `'do_not_pad'`: No padding (i.e., can output a batch with sequences of different lengths).
max_length (`int`, *optional*):
Maximum length of the returned list and optionally padding length (see above).
pad_to_multiple_of (`int`, *optional*):
If set will pad the sequence to a multiple of the provided value.
This is especially useful to enable the use of Tensor Cores on NVIDIA hardware with compute capability >=
7.5 (Volta).
return_tensors (`str`, *optional*, defaults to `"pt"`):
The type of Tensor to return. Allowable values are "np", "pt" and "tf".
"""
tokenizer: PreTrainedTokenizerBase
padding: Union[bool, str, PaddingStrategy] = True
max_length: Optional[int] = None
pad_to_multiple_of: Optional[int] = None
return_tensors: str = "pt"
def __call__(self, features: List[Dict[str, Any]]) -> Dict[str, Any]:
batch = pad_without_fast_tokenizer_warning(
self.tokenizer,
features,
padding=self.padding,
max_length=self.max_length,
pad_to_multiple_of=self.pad_to_multiple_of,
return_tensors=self.return_tensors,
)
if "label" in batch:
batch["labels"] = batch["label"]
del batch["label"]
if "label_ids" in batch:
batch["labels"] = batch["label_ids"]
del batch["label_ids"]
return batch
@dataclass
class DataCollatorForTokenClassification(DataCollatorMixin):
"""
Data collator that will dynamically pad the inputs received, as well as the labels.
Args:
tokenizer ([`PreTrainedTokenizer`] or [`PreTrainedTokenizerFast`]):
The tokenizer used for encoding the data.
padding (`bool`, `str` or [`~utils.PaddingStrategy`], *optional*, defaults to `True`):
Select a strategy to pad the returned sequences (according to the model's padding side and padding index)
among:
- `True` or `'longest'` (default): Pad to the longest sequence in the batch (or no padding if only a single
sequence is provided).
- `'max_length'`: Pad to a maximum length specified with the argument `max_length` or to the maximum
acceptable input length for the model if that argument is not provided.
- `False` or `'do_not_pad'`: No padding (i.e., can output a batch with sequences of different lengths).
max_length (`int`, *optional*):
Maximum length of the returned list and optionally padding length (see above).
pad_to_multiple_of (`int`, *optional*):
If set will pad the sequence to a multiple of the provided value.
This is especially useful to enable the use of Tensor Cores on NVIDIA hardware with compute capability >=
7.5 (Volta).
label_pad_token_id (`int`, *optional*, defaults to -100):
The id to use when padding the labels (-100 will be automatically ignore by PyTorch loss functions).
return_tensors (`str`, *optional*, defaults to `"pt"`):
The type of Tensor to return. Allowable values are "np", "pt" and "tf".
"""
tokenizer: PreTrainedTokenizerBase
padding: Union[bool, str, PaddingStrategy] = True
max_length: Optional[int] = None
pad_to_multiple_of: Optional[int] = None
label_pad_token_id: int = -100
return_tensors: str = "pt"
def torch_call(self, features):
import torch
label_name = "label" if "label" in features[0].keys() else "labels"
labels = [feature[label_name] for feature in features] if label_name in features[0].keys() else None
no_labels_features = [{k: v for k, v in feature.items() if k != label_name} for feature in features]
batch = pad_without_fast_tokenizer_warning(
self.tokenizer,
no_labels_features,
padding=self.padding,
max_length=self.max_length,
pad_to_multiple_of=self.pad_to_multiple_of,
return_tensors="pt",
)
if labels is None:
return batch
sequence_length = batch["input_ids"].shape[1]
padding_side = self.tokenizer.padding_side
def to_list(tensor_or_iterable):
if isinstance(tensor_or_iterable, torch.Tensor):
return tensor_or_iterable.tolist()
return list(tensor_or_iterable)
if padding_side == "right":
batch[label_name] = [
to_list(label) + [self.label_pad_token_id] * (sequence_length - len(label)) for label in labels
]
else:
batch[label_name] = [
[self.label_pad_token_id] * (sequence_length - len(label)) + to_list(label) for label in labels
]
batch[label_name] = torch.tensor(batch[label_name], dtype=torch.int64)
return batch
def tf_call(self, features):
import tensorflow as tf
label_name = "label" if "label" in features[0].keys() else "labels"
labels = [feature[label_name] for feature in features] if label_name in features[0].keys() else None
batch = pad_without_fast_tokenizer_warning(
self.tokenizer,
features,
padding=self.padding,
max_length=self.max_length,
pad_to_multiple_of=self.pad_to_multiple_of,
# Conversion to tensors will fail if we have labels as they are not of the same length yet.
return_tensors="tf" if labels is None else None,
)
if labels is None:
return batch
sequence_length = tf.convert_to_tensor(batch["input_ids"]).shape[1]
padding_side = self.tokenizer.padding_side
if padding_side == "right":
batch["labels"] = [
list(label) + [self.label_pad_token_id] * (sequence_length - len(label)) for label in labels
]
else:
batch["labels"] = [
[self.label_pad_token_id] * (sequence_length - len(label)) + list(label) for label in labels
]
batch = {k: tf.convert_to_tensor(v, dtype=tf.int64) for k, v in batch.items()}
return batch
def numpy_call(self, features):
label_name = "label" if "label" in features[0].keys() else "labels"
labels = [feature[label_name] for feature in features] if label_name in features[0].keys() else None
batch = pad_without_fast_tokenizer_warning(
self.tokenizer,
features,
padding=self.padding,
max_length=self.max_length,
pad_to_multiple_of=self.pad_to_multiple_of,
# Conversion to tensors will fail if we have labels as they are not of the same length yet.
return_tensors="np" if labels is None else None,
)
if labels is None:
return batch
sequence_length = np.array(batch["input_ids"]).shape[1]
padding_side = self.tokenizer.padding_side
if padding_side == "right":
batch["labels"] = [
list(label) + [self.label_pad_token_id] * (sequence_length - len(label)) for label in labels
]
else:
batch["labels"] = [
[self.label_pad_token_id] * (sequence_length - len(label)) + list(label) for label in labels
]
batch = {k: np.array(v, dtype=np.int64) for k, v in batch.items()}
return batch
def _torch_collate_batch(examples, tokenizer, pad_to_multiple_of: Optional[int] = None):
"""Collate `examples` into a batch, using the information in `tokenizer` for padding if necessary."""
import torch
# Tensorize if necessary.
if isinstance(examples[0], (list, tuple, np.ndarray)):
examples = [torch.tensor(e, dtype=torch.long) for e in examples]
length_of_first = examples[0].size(0)
# Check if padding is necessary.
are_tensors_same_length = all(x.size(0) == length_of_first for x in examples)
if are_tensors_same_length and (pad_to_multiple_of is None or length_of_first % pad_to_multiple_of == 0):
if not isinstance(examples, torch.Tensor):
return torch.stack(examples, dim=0)
# If yes, check if we have a `pad_token`.
if tokenizer.pad_token is None:
raise ValueError(
"You are attempting to pad samples but the tokenizer you are using"
f" ({tokenizer.__class__.__name__}) does not have a pad token."
)
# Creating the full tensor and filling it with our data.
max_length = max(x.size(0) for x in examples)
if pad_to_multiple_of is not None and (max_length % pad_to_multiple_of != 0):
max_length = ((max_length // pad_to_multiple_of) + 1) * pad_to_multiple_of
result = examples[0].new_full([len(examples), max_length], tokenizer.pad_token_id)
for i, example in enumerate(examples):
if tokenizer.padding_side == "right":
result[i, : example.shape[0]] = example
else:
result[i, -example.shape[0] :] = example
return result
def _tf_collate_batch(examples, tokenizer, pad_to_multiple_of: Optional[int] = None):
import tensorflow as tf
"""Collate `examples` into a batch, using the information in `tokenizer` for padding if necessary."""
# Tensorize if necessary.
if isinstance(examples[0], (list, tuple)):
examples = [tf.convert_to_tensor(e, dtype=tf.int64) for e in examples]
# Check if padding is necessary.
length_of_first = len(examples[0])
are_tensors_same_length = all(len(x) == length_of_first for x in examples)
if are_tensors_same_length and (pad_to_multiple_of is None or length_of_first % pad_to_multiple_of == 0):
return tf.stack(examples, axis=0)
# If yes, check if we have a `pad_token`.
if tokenizer.pad_token is None:
raise ValueError(
"You are attempting to pad samples but the tokenizer you are using"
f" ({tokenizer.__class__.__name__}) does not have a pad token."
)
# Creating the full tensor and filling it with our data.
max_length = max(len(x) for x in examples)
if pad_to_multiple_of is not None and (max_length % pad_to_multiple_of != 0):
max_length = ((max_length // pad_to_multiple_of) + 1) * pad_to_multiple_of
# result = examples[0].new_full([len(examples), max_length], tokenizer.pad_token_id)
result = []
rank = tf.rank(examples[0])
paddings = np.zeros((rank, 2), dtype=np.int32)
for example in examples:
if tokenizer.padding_side == "right":
paddings[0, 1] = max_length - len(example)
else:
paddings[0, 0] = max_length - len(example)
result.append(tf.pad(example, paddings, constant_values=tokenizer.pad_token_id))
return tf.stack(result, axis=0)
def _numpy_collate_batch(examples, tokenizer, pad_to_multiple_of: Optional[int] = None):
"""Collate `examples` into a batch, using the information in `tokenizer` for padding if necessary."""
# Tensorize if necessary.
if isinstance(examples[0], (list, tuple)):
examples = [np.array(e, dtype=np.int64) for e in examples]
# Check if padding is necessary.
length_of_first = len(examples[0])
are_tensors_same_length = all(len(x) == length_of_first for x in examples)
if are_tensors_same_length and (pad_to_multiple_of is None or length_of_first % pad_to_multiple_of == 0):
return np.stack(examples, axis=0)
# If yes, check if we have a `pad_token`.
if tokenizer.pad_token is None:
raise ValueError(
"You are attempting to pad samples but the tokenizer you are using"
f" ({tokenizer.__class__.__name__}) does not have a pad token."
)
# Creating the full tensor and filling it with our data.
max_length = max(len(x) for x in examples)
if pad_to_multiple_of is not None and (max_length % pad_to_multiple_of != 0):
max_length = ((max_length // pad_to_multiple_of) + 1) * pad_to_multiple_of
result = np.full(shape=(len(examples), max_length), fill_value=tokenizer.pad_token_id, dtype=examples[0].dtype)
for i, example in enumerate(examples):
if tokenizer.padding_side == "right":
result[i, : example.shape[0]] = example
else:
result[i, -example.shape[0] :] = example
return result
def tolist(x):
if isinstance(x, list):
return x
elif hasattr(x, "numpy"): # Checks for TF tensors without needing the import
x = x.numpy()
return x.tolist()
@dataclass
class DataCollatorForSeq2Seq:
"""
Data collator that will dynamically pad the inputs received, as well as the labels.
Args:
tokenizer ([`PreTrainedTokenizer`] or [`PreTrainedTokenizerFast`]):
The tokenizer used for encoding the data.
model ([`PreTrainedModel`], *optional*):
The model that is being trained. If set and has the *prepare_decoder_input_ids_from_labels*, use it to
prepare the *decoder_input_ids*
This is useful when using *label_smoothing* to avoid calculating loss twice.
padding (`bool`, `str` or [`~utils.PaddingStrategy`], *optional*, defaults to `True`):
Select a strategy to pad the returned sequences (according to the model's padding side and padding index)
among:
- `True` or `'longest'` (default): Pad to the longest sequence in the batch (or no padding if only a single
sequence is provided).
- `'max_length'`: Pad to a maximum length specified with the argument `max_length` or to the maximum
acceptable input length for the model if that argument is not provided.
- `False` or `'do_not_pad'`: No padding (i.e., can output a batch with sequences of different lengths).
max_length (`int`, *optional*):
Maximum length of the returned list and optionally padding length (see above).
pad_to_multiple_of (`int`, *optional*):
If set will pad the sequence to a multiple of the provided value.
This is especially useful to enable the use of Tensor Cores on NVIDIA hardware with compute capability >=
7.5 (Volta).
label_pad_token_id (`int`, *optional*, defaults to -100):
The id to use when padding the labels (-100 will be automatically ignored by PyTorch loss functions).
return_tensors (`str`, *optional*, defaults to `"pt"`):
The type of Tensor to return. Allowable values are "np", "pt" and "tf".
"""
tokenizer: PreTrainedTokenizerBase
model: Optional[Any] = None
padding: Union[bool, str, PaddingStrategy] = True
max_length: Optional[int] = None
pad_to_multiple_of: Optional[int] = None
label_pad_token_id: int = -100
return_tensors: str = "pt"
def __call__(self, features, return_tensors=None):
if return_tensors is None:
return_tensors = self.return_tensors
label_name = "label" if "label" in features[0].keys() else "labels"
labels = [feature[label_name] for feature in features] if label_name in features[0].keys() else None
# reconvert list[None] to None if necessary
# this might occur when we pass {..., "labels": None}
if labels is not None and all(label is None for label in labels):
labels = None
non_labels_features = [{k: v for k, v in feature.items() if k != label_name} for feature in features]
# run through tokenizer without labels to ensure no side effects
batch = pad_without_fast_tokenizer_warning(
self.tokenizer,
non_labels_features,
padding=self.padding,
max_length=self.max_length,
pad_to_multiple_of=self.pad_to_multiple_of,
return_tensors=return_tensors,
)
# we have to pad the labels manually as we cannot rely on `tokenizer.pad` and we need them to be of the same length to return tensors
no_padding = self.padding is False or self.padding == PaddingStrategy.DO_NOT_PAD
if labels is not None:
if no_padding:
if isinstance(features[0][label_name], list):
batch["labels"] = list(labels)
else:
batch["labels"] = [np.concatenate([label, []]) for label in labels]
else:
max_padding = self.padding == PaddingStrategy.MAX_LENGTH and self.max_length is not None
max_label_length = max(len(l) for l in labels) if not max_padding else self.max_length
if self.pad_to_multiple_of is not None:
max_label_length = (
(max_label_length + self.pad_to_multiple_of - 1)
// self.pad_to_multiple_of
* self.pad_to_multiple_of
)
padding_side = self.tokenizer.padding_side
if isinstance(features[0][label_name], list):
batch["labels"] = [
label + [self.label_pad_token_id] * (max_label_length - len(label))
if padding_side == "right"
else [self.label_pad_token_id] * (max_label_length - len(label)) + label
for label in labels
]
else:
batch["labels"] = [
np.concatenate(
[
label,
np.array([self.label_pad_token_id] * (max_label_length - len(label)), dtype=np.int64),
]
)
if padding_side == "right"
else np.concatenate(
[
np.array([self.label_pad_token_id] * (max_label_length - len(label)), dtype=np.int64),
label,
]
)
for label in labels
]
# reintroduce side effects via tokenizer that return respective datatypes for the `return_tensors` argument
if batch.get("labels", None) is not None:
if return_tensors == "pt":
import torch
batch["labels"] = torch.tensor(batch["labels"], dtype=torch.int64)
elif return_tensors == "tf":
import tensorflow as tf
batch["labels"] = tf.constant(batch["labels"], dtype=tf.int64)
else:
batch["labels"] = np.array(batch["labels"], dtype=np.int64)
else:
batch["labels"] = None
# prepare decoder_input_ids
if (
labels is not None
and self.model is not None
and hasattr(self.model, "prepare_decoder_input_ids_from_labels")
):
decoder_input_ids = self.model.prepare_decoder_input_ids_from_labels(labels=batch["labels"])
batch["decoder_input_ids"] = decoder_input_ids
return batch
@dataclass
class DataCollatorForLanguageModeling(DataCollatorMixin):
"""
Data collator used for language modeling. Inputs are dynamically padded to the maximum length of a batch if they
are not all of the same length.
Args:
tokenizer ([`PreTrainedTokenizer`] or [`PreTrainedTokenizerFast`]):
The tokenizer used for encoding the data.
mlm (`bool`, *optional*, defaults to `True`):
Whether or not to use masked language modeling. If set to `False`, the labels are the same as the inputs
with the padding tokens ignored (by setting them to -100). Otherwise, the labels are -100 for non-masked
tokens and the value to predict for the masked token.
mlm_probability (`float`, *optional*, defaults to 0.15):
The probability with which to (randomly) mask tokens in the input, when `mlm` is set to `True`.
pad_to_multiple_of (`int`, *optional*):
If set will pad the sequence to a multiple of the provided value.
return_tensors (`str`):
The type of Tensor to return. Allowable values are "np", "pt" and "tf".
For best performance, this data collator should be used with a dataset having items that are dictionaries or
BatchEncoding, with the `"special_tokens_mask"` key, as returned by a [`PreTrainedTokenizer`] or a
[`PreTrainedTokenizerFast`] with the argument `return_special_tokens_mask=True`.
"""
tokenizer: PreTrainedTokenizerBase
mlm: bool = True
mlm_probability: float = 0.15
pad_to_multiple_of: Optional[int] = None
tf_experimental_compile: bool = False
return_tensors: str = "pt"
def __post_init__(self):
if self.mlm and self.tokenizer.mask_token is None:
raise ValueError(
"This tokenizer does not have a mask token which is necessary for masked language modeling. "
"You should pass `mlm=False` to train on causal language modeling instead."
)
if self.tf_experimental_compile:
import tensorflow as tf
self.tf_mask_tokens = tf.function(self.tf_mask_tokens, jit_compile=True)
@staticmethod
def tf_bernoulli(shape, probability):
import tensorflow as tf
prob_matrix = tf.fill(shape, probability)
return tf.cast(prob_matrix - tf.random.uniform(shape, 0, 1) >= 0, tf.bool)
def tf_mask_tokens(
self, inputs: Any, vocab_size, mask_token_id, special_tokens_mask: Optional[Any] = None
) -> Tuple[Any, Any]:
"""
Prepare masked tokens inputs/labels for masked language modeling: 80% MASK, 10% random, 10% original.
"""
import tensorflow as tf
mask_token_id = tf.cast(mask_token_id, inputs.dtype)
input_shape = tf.shape(inputs)
# 1 for a special token, 0 for a normal token in the special tokens mask
# We sample a few tokens in each sequence for MLM training (with probability `self.mlm_probability`)
masked_indices = self.tf_bernoulli(input_shape, self.mlm_probability) & ~special_tokens_mask
# Replace unmasked indices with -100 in the labels since we only compute loss on masked tokens
labels = tf.where(masked_indices, inputs, -100)
# 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
indices_replaced = self.tf_bernoulli(input_shape, 0.8) & masked_indices
inputs = tf.where(indices_replaced, mask_token_id, inputs)
# 10% of the time, we replace masked input tokens with random word
indices_random = self.tf_bernoulli(input_shape, 0.5) & masked_indices & ~indices_replaced
random_words = tf.random.uniform(input_shape, maxval=vocab_size, dtype=inputs.dtype)
inputs = tf.where(indices_random, random_words, inputs)
# The rest of the time (10% of the time) we keep the masked input tokens unchanged
return inputs, labels
def tf_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
import tensorflow as tf
# Handle dict or lists with proper padding and conversion to tensor.
if isinstance(examples[0], Mapping):
batch = pad_without_fast_tokenizer_warning(
self.tokenizer, examples, return_tensors="tf", pad_to_multiple_of=self.pad_to_multiple_of
)
else:
batch = {
"input_ids": _tf_collate_batch(examples, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
}
# If special token mask has been preprocessed, pop it from the dict.
special_tokens_mask = batch.pop("special_tokens_mask", None)
if self.mlm:
if special_tokens_mask is None:
special_tokens_mask = [
self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True)
for val in batch["input_ids"].numpy().tolist()
]
# Cannot directly create as bool
special_tokens_mask = tf.cast(tf.convert_to_tensor(special_tokens_mask, dtype=tf.int64), tf.bool)
else:
special_tokens_mask = tf.cast(special_tokens_mask, tf.bool)
batch["input_ids"], batch["labels"] = self.tf_mask_tokens(
tf.cast(batch["input_ids"], tf.int64),
special_tokens_mask=special_tokens_mask,
mask_token_id=self.tokenizer.mask_token_id,
vocab_size=len(self.tokenizer),
)
else:
labels = batch["input_ids"]
if self.tokenizer.pad_token_id is not None:
# Replace self.tokenizer.pad_token_id with -100
labels = tf.where(labels == self.tokenizer.pad_token_id, -100, labels)
else:
labels = tf.identity(labels) # Makes a copy, just in case
batch["labels"] = labels
return batch
def torch_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
# Handle dict or lists with proper padding and conversion to tensor.
if isinstance(examples[0], Mapping):
batch = pad_without_fast_tokenizer_warning(
self.tokenizer, examples, return_tensors="pt", pad_to_multiple_of=self.pad_to_multiple_of
)
else:
batch = {
"input_ids": _torch_collate_batch(examples, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
}
# If special token mask has been preprocessed, pop it from the dict.
special_tokens_mask = batch.pop("special_tokens_mask", None)
if self.mlm:
batch["input_ids"], batch["labels"] = self.torch_mask_tokens(
batch["input_ids"], special_tokens_mask=special_tokens_mask
)
else:
labels = batch["input_ids"].clone()
if self.tokenizer.pad_token_id is not None:
labels[labels == self.tokenizer.pad_token_id] = -100
batch["labels"] = labels
return batch
def torch_mask_tokens(self, inputs: Any, special_tokens_mask: Optional[Any] = None) -> Tuple[Any, Any]:
"""
Prepare masked tokens inputs/labels for masked language modeling: 80% MASK, 10% random, 10% original.
"""
import torch
labels = inputs.clone()
# We sample a few tokens in each sequence for MLM training (with probability `self.mlm_probability`)
probability_matrix = torch.full(labels.shape, self.mlm_probability)
if special_tokens_mask is None:
special_tokens_mask = [
self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()
]
special_tokens_mask = torch.tensor(special_tokens_mask, dtype=torch.bool)
else:
special_tokens_mask = special_tokens_mask.bool()
probability_matrix.masked_fill_(special_tokens_mask, value=0.0)
masked_indices = torch.bernoulli(probability_matrix).bool()
labels[~masked_indices] = -100 # We only compute loss on masked tokens
# 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
indices_replaced = torch.bernoulli(torch.full(labels.shape, 0.8)).bool() & masked_indices
inputs[indices_replaced] = self.tokenizer.convert_tokens_to_ids(self.tokenizer.mask_token)
# 10% of the time, we replace masked input tokens with random word
indices_random = torch.bernoulli(torch.full(labels.shape, 0.5)).bool() & masked_indices & ~indices_replaced
random_words = torch.randint(len(self.tokenizer), labels.shape, dtype=torch.long)
inputs[indices_random] = random_words[indices_random]
# The rest of the time (10% of the time) we keep the masked input tokens unchanged
return inputs, labels
def numpy_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
# Handle dict or lists with proper padding and conversion to tensor.
if isinstance(examples[0], Mapping):
batch = pad_without_fast_tokenizer_warning(
self.tokenizer, examples, return_tensors="np", pad_to_multiple_of=self.pad_to_multiple_of
)
else:
batch = {
"input_ids": _numpy_collate_batch(examples, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
}
# If special token mask has been preprocessed, pop it from the dict.
special_tokens_mask = batch.pop("special_tokens_mask", None)
if self.mlm:
batch["input_ids"], batch["labels"] = self.numpy_mask_tokens(
batch["input_ids"], special_tokens_mask=special_tokens_mask
)
else:
labels = np.copy(batch["input_ids"])
if self.tokenizer.pad_token_id is not None:
labels[labels == self.tokenizer.pad_token_id] = -100
batch["labels"] = labels
return batch
def numpy_mask_tokens(self, inputs: Any, special_tokens_mask: Optional[Any] = None) -> Tuple[Any, Any]:
"""
Prepare masked tokens inputs/labels for masked language modeling: 80% MASK, 10% random, 10% original.
"""
labels = np.copy(inputs)
# We sample a few tokens in each sequence for MLM training (with probability `self.mlm_probability`)
probability_matrix = np.full(labels.shape, self.mlm_probability)
if special_tokens_mask is None:
special_tokens_mask = [
self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()
]
special_tokens_mask = np.array(special_tokens_mask, dtype=bool)
else:
special_tokens_mask = special_tokens_mask.astype(bool)
probability_matrix[special_tokens_mask] = 0
# Numpy doesn't have bernoulli, so we use a binomial with 1 trial
masked_indices = np.random.binomial(1, probability_matrix, size=probability_matrix.shape).astype(bool)
labels[~masked_indices] = -100 # We only compute loss on masked tokens
# 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
indices_replaced = np.random.binomial(1, 0.8, size=labels.shape).astype(bool) & masked_indices
inputs[indices_replaced] = self.tokenizer.mask_token_id
# 10% of the time, we replace masked input tokens with random word
# indices_random = torch.bernoulli(torch.full(labels.shape, 0.5)).bool() & masked_indices & ~indices_replaced
indices_random = (
np.random.binomial(1, 0.5, size=labels.shape).astype(bool) & masked_indices & ~indices_replaced
)
random_words = np.random.randint(
low=0, high=len(self.tokenizer), size=np.count_nonzero(indices_random), dtype=np.int64
)
inputs[indices_random] = random_words
# The rest of the time (10% of the time) we keep the masked input tokens unchanged
return inputs, labels
@dataclass
class DataCollatorForWholeWordMask(DataCollatorForLanguageModeling):
"""
Data collator used for language modeling that masks entire words.
- collates batches of tensors, honoring their tokenizer's pad_token
- preprocesses batches for masked language modeling
This collator relies on details of the implementation of subword tokenization by [`BertTokenizer`], specifically
that subword tokens are prefixed with *##*. For tokenizers that do not adhere to this scheme, this collator will
produce an output that is roughly equivalent to [`.DataCollatorForLanguageModeling`].
"""
def torch_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
if isinstance(examples[0], Mapping):
input_ids = [e["input_ids"] for e in examples]
else:
input_ids = examples
examples = [{"input_ids": e} for e in examples]
batch_input = _torch_collate_batch(input_ids, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
mask_labels = []
for e in examples:
ref_tokens = []
for id in tolist(e["input_ids"]):
token = self.tokenizer._convert_id_to_token(id)
ref_tokens.append(token)
# For Chinese tokens, we need extra inf to mark sub-word, e.g [喜,欢]-> [喜，##欢]
if "chinese_ref" in e:
ref_pos = tolist(e["chinese_ref"])
len_seq = len(e["input_ids"])
for i in range(len_seq):
if i in ref_pos:
ref_tokens[i] = "##" + ref_tokens[i]
mask_labels.append(self._whole_word_mask(ref_tokens))
batch_mask = _torch_collate_batch(mask_labels, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
inputs, labels = self.torch_mask_tokens(batch_input, batch_mask)
return {"input_ids": inputs, "labels": labels}
def tf_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
import tensorflow as tf
if isinstance(examples[0], Mapping):
input_ids = [e["input_ids"] for e in examples]
else:
input_ids = examples
examples = [{"input_ids": e} for e in examples]
batch_input = _tf_collate_batch(input_ids, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
mask_labels = []
for e in examples:
ref_tokens = []
for id in tolist(e["input_ids"]):
token = self.tokenizer._convert_id_to_token(id)
ref_tokens.append(token)
# For Chinese tokens, we need extra inf to mark sub-word, e.g [喜,欢]-> [喜，##欢]
if "chinese_ref" in e:
ref_pos = tolist(e["chinese_ref"])
len_seq = len(e["input_ids"])
for i in range(len_seq):
if i in ref_pos:
ref_tokens[i] = "##" + ref_tokens[i]
mask_labels.append(self._whole_word_mask(ref_tokens))
batch_mask = _tf_collate_batch(mask_labels, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
inputs, labels = self.tf_mask_tokens(tf.cast(batch_input, tf.int64), batch_mask)
return {"input_ids": inputs, "labels": labels}
def numpy_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
if isinstance(examples[0], Mapping):
input_ids = [e["input_ids"] for e in examples]
else:
input_ids = examples
examples = [{"input_ids": e} for e in examples]
batch_input = _numpy_collate_batch(input_ids, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
mask_labels = []
for e in examples:
ref_tokens = []
for id in tolist(e["input_ids"]):
token = self.tokenizer._convert_id_to_token(id)
ref_tokens.append(token)
# For Chinese tokens, we need extra inf to mark sub-word, e.g [喜,欢]-> [喜，##欢]
if "chinese_ref" in e:
ref_pos = tolist(e["chinese_ref"])
len_seq = len(e["input_ids"])
for i in range(len_seq):
if i in ref_pos:
ref_tokens[i] = "##" + ref_tokens[i]
mask_labels.append(self._whole_word_mask(ref_tokens))
batch_mask = _numpy_collate_batch(mask_labels, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
inputs, labels = self.numpy_mask_tokens(batch_input, batch_mask)
return {"input_ids": inputs, "labels": labels}
def _whole_word_mask(self, input_tokens: List[str], max_predictions=512):
"""
Get 0/1 labels for masked tokens with whole word mask proxy
"""
if not isinstance(self.tokenizer, (BertTokenizer, BertTokenizerFast)):
warnings.warn(
"DataCollatorForWholeWordMask is only suitable for BertTokenizer-like tokenizers. "
"Please refer to the documentation for more information."
)
cand_indexes = []
for i, token in enumerate(input_tokens):
if token == "[CLS]" or token == "[SEP]":
continue
if len(cand_indexes) >= 1 and token.startswith("##"):
cand_indexes[-1].append(i)
else:
cand_indexes.append([i])
random.shuffle(cand_indexes)
num_to_predict = min(max_predictions, max(1, int(round(len(input_tokens) * self.mlm_probability))))
masked_lms = []
covered_indexes = set()
for index_set in cand_indexes:
if len(masked_lms) >= num_to_predict:
break
# If adding a whole-word mask would exceed the maximum number of
# predictions, then just skip this candidate.
if len(masked_lms) + len(index_set) > num_to_predict:
continue
is_any_index_covered = False
for index in index_set:
if index in covered_indexes:
is_any_index_covered = True
break
if is_any_index_covered:
continue
for index in index_set:
covered_indexes.add(index)
masked_lms.append(index)
if len(covered_indexes) != len(masked_lms):
raise ValueError("Length of covered_indexes is not equal to length of masked_lms.")
mask_labels = [1 if i in covered_indexes else 0 for i in range(len(input_tokens))]
return mask_labels
def torch_mask_tokens(self, inputs: Any, mask_labels: Any) -> Tuple[Any, Any]:
"""
Prepare masked tokens inputs/labels for masked language modeling: 80% MASK, 10% random, 10% original. Set
'mask_labels' means we use whole word mask (wwm), we directly mask idxs according to it's ref.
"""
import torch
if self.tokenizer.mask_token is None:
raise ValueError(
"This tokenizer does not have a mask token which is necessary for masked language modeling. Remove the"
" --mlm flag if you want to use this tokenizer."
)
labels = inputs.clone()
# We sample a few tokens in each sequence for masked-LM training (with probability args.mlm_probability defaults to 0.15 in Bert/RoBERTa)
probability_matrix = mask_labels
special_tokens_mask = [
self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()
]
probability_matrix.masked_fill_(torch.tensor(special_tokens_mask, dtype=torch.bool), value=0.0)
if self.tokenizer.pad_token is not None:
padding_mask = labels.eq(self.tokenizer.pad_token_id)
probability_matrix.masked_fill_(padding_mask, value=0.0)
masked_indices = probability_matrix.bool()
labels[~masked_indices] = -100 # We only compute loss on masked tokens
# 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
indices_replaced = torch.bernoulli(torch.full(labels.shape, 0.8)).bool() & masked_indices
inputs[indices_replaced] = self.tokenizer.convert_tokens_to_ids(self.tokenizer.mask_token)
# 10% of the time, we replace masked input tokens with random word
indices_random = torch.bernoulli(torch.full(labels.shape, 0.5)).bool() & masked_indices & ~indices_replaced
random_words = torch.randint(len(self.tokenizer), labels.shape, dtype=torch.long)
inputs[indices_random] = random_words[indices_random]
# The rest of the time (10% of the time) we keep the masked input tokens unchanged
return inputs, labels
def tf_mask_tokens(self, inputs: Any, mask_labels: Any) -> Tuple[Any, Any]:
"""
Prepare masked tokens inputs/labels for masked language modeling: 80% MASK, 10% random, 10% original. Set
'mask_labels' means we use whole word mask (wwm), we directly mask idxs according to it's ref.
"""
import tensorflow as tf
input_shape = tf.shape(inputs)
if self.tokenizer.mask_token is None:
raise ValueError(
"This tokenizer does not have a mask token which is necessary for masked language modeling. Remove the"
" --mlm flag if you want to use this tokenizer."
)
labels = tf.identity(inputs)
# We sample a few tokens in each sequence for masked-LM training (with probability args.mlm_probability defaults to 0.15 in Bert/RoBERTa)
masked_indices = tf.cast(mask_labels, tf.bool)
special_tokens_mask = [
self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels
]
masked_indices = masked_indices & ~tf.cast(special_tokens_mask, dtype=tf.bool)
if self.tokenizer.pad_token is not None:
padding_mask = inputs == self.tokenizer.pad_token_id
masked_indices = masked_indices & ~padding_mask
# Replace unmasked indices with -100 in the labels since we only compute loss on masked tokens
labels = tf.where(masked_indices, inputs, -100)
# 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
indices_replaced = self.tf_bernoulli(input_shape, 0.8) & masked_indices
inputs = tf.where(indices_replaced, self.tokenizer.mask_token_id, inputs)
# 10% of the time, we replace masked input tokens with random word
indices_random = self.tf_bernoulli(input_shape, 0.5) & masked_indices & ~indices_replaced
random_words = tf.random.uniform(input_shape, maxval=len(self.tokenizer), dtype=tf.int64)
inputs = tf.where(indices_random, random_words, inputs)
# The rest of the time (10% of the time) we keep the masked input tokens unchanged
return inputs, labels
def numpy_mask_tokens(self, inputs: Any, mask_labels: Any) -> Tuple[Any, Any]:
"""
Prepare masked tokens inputs/labels for masked language modeling: 80% MASK, 10% random, 10% original. Set
'mask_labels' means we use whole word mask (wwm), we directly mask idxs according to it's ref.
"""
if self.tokenizer.mask_token is None:
raise ValueError(
"This tokenizer does not have a mask token which is necessary for masked language modeling. Remove the"
" --mlm flag if you want to use this tokenizer."
)
labels = np.copy(inputs)
# We sample a few tokens in each sequence for masked-LM training (with probability args.mlm_probability defaults to 0.15 in Bert/RoBERTa)
masked_indices = mask_labels.astype(bool)
special_tokens_mask = [
self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()
]
masked_indices[np.array(special_tokens_mask, dtype=bool)] = 0
if self.tokenizer.pad_token is not None:
padding_mask = labels == self.tokenizer.pad_token_id
masked_indices[padding_mask] = 0
labels[~masked_indices] = -100 # We only compute loss on masked tokens
# 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
indices_replaced = np.random.binomial(1, 0.8, size=labels.shape).astype(bool) & masked_indices
inputs[indices_replaced] = self.tokenizer.convert_tokens_to_ids(self.tokenizer.mask_token)
# 10% of the time, we replace masked input tokens with random word
# indices_random = torch.bernoulli(torch.full(labels.shape, 0.5)).bool() & masked_indices & ~indices_replaced
indices_random = (
np.random.binomial(1, 0.5, size=labels.shape).astype(bool) & masked_indices & ~indices_replaced
)
random_words = np.random.randint(low=0, high=len(self.tokenizer), size=labels.shape, dtype=np.int64)
inputs[indices_random] = random_words[indices_random]
# The rest of the time (10% of the time) we keep the masked input tokens unchanged
return inputs, labels
@dataclass
class DataCollatorForSOP(DataCollatorForLanguageModeling):
"""
Data collator used for sentence order prediction task.
- collates batches of tensors, honoring their tokenizer's pad_token
- preprocesses batches for both masked language modeling and sentence order prediction
"""
def __init__(self, *args, **kwargs):
warnings.warn(
"DataCollatorForSOP is deprecated and will be removed in a future version, you can now use "
"DataCollatorForLanguageModeling instead.",
FutureWarning,
)
def __call__(self, examples: List[Dict[str, Any]]) -> Dict[str, Any]:
import torch
from torch.nn.utils.rnn import pad_sequence
input_ids = [example["input_ids"] for example in examples]
input_ids = _torch_collate_batch(input_ids, self.tokenizer)
input_ids, labels, attention_mask = self.mask_tokens(input_ids)
token_type_ids = [example["token_type_ids"] for example in examples]
# size of segment_ids varied because randomness, padding zero to the end as the original implementation
token_type_ids = pad_sequence(token_type_ids, batch_first=True, padding_value=self.tokenizer.pad_token_id)
sop_label_list = [example["sentence_order_label"] for example in examples]
sentence_order_label = torch.stack(sop_label_list)
return {
"input_ids": input_ids,
"labels": labels,
"attention_mask": attention_mask,
"token_type_ids": token_type_ids,
"sentence_order_label": sentence_order_label,
}
def mask_tokens(self, inputs: Any) -> Tuple[Any, Any, Any]:
"""
Prepare masked tokens inputs/labels/attention_mask for masked language modeling: 80% MASK, 10% random, 10%
original. N-gram not applied yet.
"""
import torch
if self.tokenizer.mask_token is None:
raise ValueError(
"This tokenizer does not have a mask token which is necessary for masked language modeling. Remove the"
" --mlm flag if you want to use this tokenizer."
)
labels = inputs.clone()
# We sample a few tokens in each sequence for masked-LM training (with probability args.mlm_probability defaults to 0.15 in Bert/RoBERTa)
probability_matrix = torch.full(labels.shape, self.mlm_probability)
special_tokens_mask = [
self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()
]
probability_matrix.masked_fill_(torch.tensor(special_tokens_mask, dtype=torch.bool), value=0.0)
if self.tokenizer.pad_token is not None:
padding_mask = labels.eq(self.tokenizer.pad_token_id)
probability_matrix.masked_fill_(padding_mask, value=0.0)
masked_indices = torch.bernoulli(probability_matrix).bool()
# probability be `1` (masked), however in albert model attention mask `0` means masked, revert the value
attention_mask = (~masked_indices).float()
if self.tokenizer.pad_token is not None:
attention_padding_mask = labels.eq(self.tokenizer.pad_token_id)
attention_mask.masked_fill_(attention_padding_mask, value=1.0)
labels[~masked_indices] = -100 # We only compute loss on masked tokens, -100 is default for CE compute
# 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
indices_replaced = torch.bernoulli(torch.full(labels.shape, 0.8)).bool() & masked_indices
inputs[indices_replaced] = self.tokenizer.convert_tokens_to_ids(self.tokenizer.mask_token)
# 10% of the time, we replace masked input tokens with random word
indices_random = torch.bernoulli(torch.full(labels.shape, 0.5)).bool() & masked_indices & ~indices_replaced
random_words = torch.randint(len(self.tokenizer), labels.shape, dtype=torch.long)
inputs[indices_random] = random_words[indices_random]
# The rest of the time (10% of the time) we keep the masked input tokens unchanged
return inputs, labels, attention_mask
@dataclass
class DataCollatorForPermutationLanguageModeling(DataCollatorMixin):
"""
Data collator used for permutation language modeling.
- collates batches of tensors, honoring their tokenizer's pad_token
- preprocesses batches for permutation language modeling with procedures specific to XLNet
"""
tokenizer: PreTrainedTokenizerBase
plm_probability: float = 1 / 6
max_span_length: int = 5 # maximum length of a span of masked tokens
return_tensors: str = "pt"
def torch_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
if isinstance(examples[0], Mapping):
examples = [e["input_ids"] for e in examples]
batch = _torch_collate_batch(examples, self.tokenizer)
inputs, perm_mask, target_mapping, labels = self.torch_mask_tokens(batch)
return {"input_ids": inputs, "perm_mask": perm_mask, "target_mapping": target_mapping, "labels": labels}
def tf_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
if isinstance(examples[0], Mapping):
examples = [e["input_ids"] for e in examples]
batch = _tf_collate_batch(examples, self.tokenizer)
inputs, perm_mask, target_mapping, labels = self.tf_mask_tokens(batch)
return {"input_ids": inputs, "perm_mask": perm_mask, "target_mapping": target_mapping, "labels": labels}
def numpy_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
if isinstance(examples[0], Mapping):
examples = [e["input_ids"] for e in examples]
batch = _numpy_collate_batch(examples, self.tokenizer)
inputs, perm_mask, target_mapping, labels = self.numpy_mask_tokens(batch)
return {"input_ids": inputs, "perm_mask": perm_mask, "target_mapping": target_mapping, "labels": labels}
def torch_mask_tokens(self, inputs: Any) -> Tuple[Any, Any, Any, Any]:
"""
The masked tokens to be predicted for a particular sequence are determined by the following algorithm:
0. Start from the beginning of the sequence by setting `cur_len = 0` (number of tokens processed so far).
1. Sample a `span_length` from the interval `[1, max_span_length]` (length of span of tokens to be masked)
2. Reserve a context of length `context_length = span_length / plm_probability` to surround span to be
masked
3. Sample a starting point `start_index` from the interval `[cur_len, cur_len + context_length -
span_length]` and mask tokens `start_index:start_index + span_length`
4. Set `cur_len = cur_len + context_length`. If `cur_len < max_len` (i.e. there are tokens remaining in the
sequence to be processed), repeat from Step 1.
"""
import torch
if self.tokenizer.mask_token is None:
raise ValueError(
"This tokenizer does not have a mask token which is necessary for permutation language modeling."
" Please add a mask token if you want to use this tokenizer."
)
if inputs.size(1) % 2 != 0:
raise ValueError(
"This collator requires that sequence lengths be even to create a leakage-free perm_mask. Please see"
" relevant comments in source code for details."
)
labels = inputs.clone()
# Creating the mask and target_mapping tensors
masked_indices = torch.full(labels.shape, 0, dtype=torch.bool)
target_mapping = torch.zeros((labels.size(0), labels.size(1), labels.size(1)), dtype=torch.float32)
for i in range(labels.size(0)):
# Start from the beginning of the sequence by setting `cur_len = 0` (number of tokens processed so far).
cur_len = 0
max_len = labels.size(1)
while cur_len < max_len:
# Sample a `span_length` from the interval `[1, max_span_length]` (length of span of tokens to be masked)
span_length = torch.randint(1, self.max_span_length + 1, (1,)).item()
# Reserve a context of length `context_length = span_length / plm_probability` to surround the span to be masked
context_length = int(span_length / self.plm_probability)
# Sample a starting point `start_index` from the interval `[cur_len, cur_len + context_length - span_length]` and mask tokens `start_index:start_index + span_length`
start_index = cur_len + torch.randint(context_length - span_length + 1, (1,)).item()
masked_indices[i, start_index : start_index + span_length] = 1
# Set `cur_len = cur_len + context_length`
cur_len += context_length
# Since we're replacing non-masked tokens with -100 in the labels tensor instead of skipping them altogether,
# the i-th predict corresponds to the i-th token.
target_mapping[i] = torch.eye(labels.size(1))
special_tokens_mask = torch.tensor(
[self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()],
dtype=torch.bool,
)
masked_indices.masked_fill_(special_tokens_mask, value=0.0)
if self.tokenizer.pad_token is not None:
padding_mask = labels.eq(self.tokenizer.pad_token_id)
masked_indices.masked_fill_(padding_mask, value=0.0)
# Mask indicating non-functional tokens, where functional tokens are [SEP], [CLS], padding, etc.
non_func_mask = ~(padding_mask | special_tokens_mask)
inputs[masked_indices] = self.tokenizer.mask_token_id
labels[~masked_indices] = -100 # We only compute loss on masked tokens
perm_mask = torch.zeros((labels.size(0), labels.size(1), labels.size(1)), dtype=torch.float32)
for i in range(labels.size(0)):
# Generate permutation indices i.e. sample a random factorisation order for the sequence. This will
# determine which tokens a given token can attend to (encoded in `perm_mask`).
# Note: Length of token sequence being permuted has to be less than or equal to reused sequence length
# (see documentation for `mems`), otherwise information may leak through due to reuse. In this implementation,
# we assume that reused length is half of sequence length and permutation length is equal to reused length.
# This requires that the sequence length be even.
# Create a linear factorisation order
perm_index = torch.arange(labels.size(1))
# Split this into two halves, assuming that half the sequence is reused each time
perm_index = perm_index.reshape((-1, labels.size(1) // 2)).transpose(0, 1)
# Permute the two halves such that they do not cross over
perm_index = perm_index[torch.randperm(labels.size(1) // 2)]
# Flatten this out into the desired permuted factorisation order
perm_index = torch.flatten(perm_index.transpose(0, 1))
# Set the permutation indices of non-masked (non-functional) tokens to the
# smallest index (-1) so that:
# (1) They can be seen by all other positions
# (2) They cannot see masked positions, so there won't be information leak
perm_index.masked_fill_(~masked_indices[i] & non_func_mask[i], -1)
# The logic for whether the i-th token can attend on the j-th token based on the factorisation order:
# 0 (can attend): If perm_index[i] > perm_index[j] or j is neither masked nor a functional token
# 1 (cannot attend): If perm_index[i] <= perm_index[j] and j is either masked or a functional token
perm_mask[i] = (
perm_index.reshape((labels.size(1), 1)) <= perm_index.reshape((1, labels.size(1)))
) & masked_indices[i]
return inputs.long(), perm_mask, target_mapping, labels.long()
def tf_mask_tokens(self, inputs: Any) -> Tuple[Any, Any, Any, Any]:
"""
The masked tokens to be predicted for a particular sequence are determined by the following algorithm:
0. Start from the beginning of the sequence by setting `cur_len = 0` (number of tokens processed so far).
1. Sample a `span_length` from the interval `[1, max_span_length]` (length of span of tokens to be masked)
2. Reserve a context of length `context_length = span_length / plm_probability` to surround span to be
masked
3. Sample a starting point `start_index` from the interval `[cur_len, cur_len + context_length -
span_length]` and mask tokens `start_index:start_index + span_length`
4. Set `cur_len = cur_len + context_length`. If `cur_len < max_len` (i.e. there are tokens remaining in the
sequence to be processed), repeat from Step 1.
"""
import tensorflow as tf
if self.tokenizer.mask_token is None:
raise ValueError(
"This tokenizer does not have a mask token which is necessary for permutation language modeling."
" Please add a mask token if you want to use this tokenizer."
)
if tf.shape(inputs)[1] % 2 != 0:
raise ValueError(
"This collator requires that sequence lengths be even to create a leakage-free perm_mask. Please see"
" relevant comments in source code for details."
)
labels = tf.identity(inputs)
# Creating the mask and target_mapping tensors
masked_indices = np.full(labels.shape.as_list(), 0, dtype=bool)
labels_shape = tf.shape(labels)
target_mapping = np.zeros((labels_shape[0], labels_shape[1], labels_shape[1]), dtype=np.float32)
for i in range(len(labels)):
# Start from the beginning of the sequence by setting `cur_len = 0` (number of tokens processed so far).
cur_len = 0
max_len = tf.shape(labels)[1]
while cur_len < max_len:
# Sample a `span_length` from the interval `[1, max_span_length]` (length of span of tokens to be masked)
span_length = randint(1, self.max_span_length + 1)
# Reserve a context of length `context_length = span_length / plm_probability` to surround the span to be masked
context_length = int(span_length / self.plm_probability)
# Sample a starting point `start_index` from the interval `[cur_len, cur_len + context_length - span_length]` and mask tokens `start_index:start_index + span_length`
start_index = cur_len + randint(0, context_length - span_length + 1)
masked_indices[i, start_index : start_index + span_length] = 1
# Set `cur_len = cur_len + context_length`
cur_len += context_length
# Since we're replacing non-masked tokens with -100 in the labels tensor instead of skipping them altogether,
# the i-th predict corresponds to the i-th token.
target_mapping[i] = np.eye(labels_shape[1])
masked_indices = tf.cast(tf.convert_to_tensor(masked_indices), dtype=tf.bool)
target_mapping = tf.convert_to_tensor(target_mapping)
special_tokens_mask = tf.convert_to_tensor(
[
self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True)
for val in labels.numpy().tolist()
],
)
special_tokens_mask = tf.cast(special_tokens_mask, dtype=tf.bool)
masked_indices = masked_indices & ~special_tokens_mask
if self.tokenizer.pad_token is not None:
padding_mask = labels == self.tokenizer.pad_token_id
masked_indices = masked_indices & ~padding_mask
# Mask indicating non-functional tokens, where functional tokens are [SEP], [CLS], padding, etc.
non_func_mask = ~(padding_mask | special_tokens_mask)
inputs = tf.where(masked_indices, self.tokenizer.mask_token_id, inputs)
labels = tf.where(masked_indices, labels, -100) # We only compute loss on masked tokens
perm_mask = []
for i in range(len(labels)):
# Generate permutation indices i.e. sample a random factorisation order for the sequence. This will
# determine which tokens a given token can attend to (encoded in `perm_mask`).
# Note: Length of token sequence being permuted has to be less than or equal to reused sequence length
# (see documentation for `mems`), otherwise information may leak through due to reuse. In this implementation,
# we assume that reused length is half of sequence length and permutation length is equal to reused length.
# This requires that the sequence length be even.
# Create a linear factorisation order
# tf.range is the equivalent of torch.arange
perm_index = tf.range(labels_shape[1])
# Split this into two halves, assuming that half the sequence is reused each time
perm_index = tf.transpose(tf.reshape(perm_index, (-1, labels_shape[1] // 2)))
# Permute the two halves such that they do not cross over
perm_index = tf.random.shuffle(perm_index) # Shuffles along the first dimension
# Flatten this out into the desired permuted factorisation order
perm_index = tf.reshape(tf.transpose(perm_index), (-1,))
# Set the permutation indices of non-masked (non-functional) tokens to the
# smallest index (-1) so that:
# (1) They can be seen by all other positions
# (2) They cannot see masked positions, so there won't be information leak
perm_index = tf.where(~masked_indices[i] & non_func_mask[i], -1, perm_index)
# The logic for whether the i-th token can attend on the j-th token based on the factorisation order:
# 0 (can attend): If perm_index[i] > perm_index[j] or j is neither masked nor a functional token
# 1 (cannot attend): If perm_index[i] <= perm_index[j] and j is either masked or a functional token
perm_mask.append(
(tf.reshape(perm_index, (labels_shape[1], 1)) <= tf.reshape(perm_index, (1, labels_shape[1])))
& masked_indices[i]
)
perm_mask = tf.stack(perm_mask, axis=0)
return tf.cast(inputs, tf.int64), tf.cast(perm_mask, tf.float32), target_mapping, tf.cast(labels, tf.int64)
def numpy_mask_tokens(self, inputs: Any) -> Tuple[Any, Any, Any, Any]:
"""
The masked tokens to be predicted for a particular sequence are determined by the following algorithm:
0. Start from the beginning of the sequence by setting `cur_len = 0` (number of tokens processed so far).
1. Sample a `span_length` from the interval `[1, max_span_length]` (length of span of tokens to be masked)
2. Reserve a context of length `context_length = span_length / plm_probability` to surround span to be
masked
3. Sample a starting point `start_index` from the interval `[cur_len, cur_len + context_length -
span_length]` and mask tokens `start_index:start_index + span_length`
4. Set `cur_len = cur_len + context_length`. If `cur_len < max_len` (i.e. there are tokens remaining in the
sequence to be processed), repeat from Step 1.
"""
if self.tokenizer.mask_token is None:
raise ValueError(
"This tokenizer does not have a mask token which is necessary for permutation language modeling."
" Please add a mask token if you want to use this tokenizer."
)
if inputs.shape[1] % 2 != 0:
raise ValueError(
"This collator requires that sequence lengths be even to create a leakage-free perm_mask. Please see"
" relevant comments in source code for details."
)
labels = np.copy(inputs)
# Creating the mask and target_mapping tensors
masked_indices = np.full(labels.shape, 0, dtype=bool)
target_mapping = np.zeros((labels.shape[0], labels.shape[1], labels.shape[1]), dtype=np.float32)
for i in range(labels.shape[0]):
# Start from the beginning of the sequence by setting `cur_len = 0` (number of tokens processed so far).
cur_len = 0
max_len = labels.shape[1]
while cur_len < max_len:
# Sample a `span_length` from the interval `[1, max_span_length]` (length of span of tokens to be masked)
span_length = randint(1, self.max_span_length + 1)
# Reserve a context of length `context_length = span_length / plm_probability` to surround the span to be masked
context_length = int(span_length / self.plm_probability)
# Sample a starting point `start_index` from the interval `[cur_len, cur_len + context_length - span_length]` and mask tokens `start_index:start_index + span_length`
start_index = cur_len + randint(0, context_length - span_length + 1)
masked_indices[i, start_index : start_index + span_length] = 1
# Set `cur_len = cur_len + context_length`
cur_len += context_length
# Since we're replacing non-masked tokens with -100 in the labels tensor instead of skipping them altogether,
# the i-th predict corresponds to the i-th token.
target_mapping[i] = np.eye(labels.shape[1])
special_tokens_mask = np.array(
[self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()],
dtype=bool,
)
masked_indices[special_tokens_mask] = 0
if self.tokenizer.pad_token is not None:
padding_mask = labels == self.tokenizer.pad_token_id
masked_indices[padding_mask] = 0.0
# Mask indicating non-functional tokens, where functional tokens are [SEP], [CLS], padding, etc.
non_func_mask = ~(padding_mask | special_tokens_mask)
inputs[masked_indices] = self.tokenizer.mask_token_id
labels[~masked_indices] = -100 # We only compute loss on masked tokens
perm_mask = np.zeros((labels.shape[0], labels.shape[1], labels.shape[1]), dtype=np.float32)
for i in range(labels.shape[0]):
# Generate permutation indices i.e. sample a random factorisation order for the sequence. This will
# determine which tokens a given token can attend to (encoded in `perm_mask`).
# Note: Length of token sequence being permuted has to be less than or equal to reused sequence length
# (see documentation for `mems`), otherwise information may leak through due to reuse. In this implementation,
# we assume that reused length is half of sequence length and permutation length is equal to reused length.
# This requires that the sequence length be even.
# Create a linear factorisation order
perm_index = np.arange(labels.shape[1])
# Split this into two halves, assuming that half the sequence is reused each time
perm_index = perm_index.reshape((-1, labels.shape[1] // 2)).T
# Permute the two halves such that they do not cross over
np.random.shuffle(perm_index)
# Flatten this out into the desired permuted factorisation order
perm_index = perm_index.T.flatten()
# Set the permutation indices of non-masked (non-functional) tokens to the
# smallest index (-1) so that:
# (1) They can be seen by all other positions
# (2) They cannot see masked positions, so there won't be information leak
perm_index[~masked_indices[i] & non_func_mask[i]] = -1
# The logic for whether the i-th token can attend on the j-th token based on the factorisation order:
# 0 (can attend): If perm_index[i] > perm_index[j] or j is neither masked nor a functional token
# 1 (cannot attend): If perm_index[i] <= perm_index[j] and j is either masked or a functional token
perm_mask[i] = (
perm_index.reshape((labels.shape[1], 1)) <= perm_index.reshape((1, labels.shape[1]))
) & masked_indices[i]
return inputs.astype(np.int64), perm_mask, target_mapping, labels.astype(np.int64)
@dataclass
class DataCollatorWithFlattening(DefaultDataCollator):
"""
Data collator used for padding free approach. Does the following:
- concatate the entire mini batch into single long sequence [1, total_tokens]
- uses `separator_id` to separate sequences within the concatenated `labels`, default value is -100
- no padding will be added, returns `input_ids`, `labels` and `position_ids`
"""
def __init__(self, *args, return_position_ids=True, separator_id=-100, **kwargs):
super().__init__(*args, **kwargs)
self.return_position_ids = return_position_ids
self.separator_id = separator_id
warnings.warn(
"Using `DataCollatorWithFlattening` will flatten the entire mini batch into single long sequence."
"Make sure your attention computation is able to handle it!"
)
def __call__(self, features, return_tensors=None, separator_id=None):
if return_tensors is None:
return_tensors = self.return_tensors
if separator_id is None:
separator_id = self.separator_id
is_labels_provided = "labels" in features[0]
ret = {"input_ids": [], "labels": []}
if self.return_position_ids:
ret.update({"position_ids": []})
for idx in range(0, len(features)):
ret["input_ids"] += features[idx]["input_ids"]
if is_labels_provided:
ret["labels"] += [separator_id] + features[idx]["labels"][1:]
else:
ret["labels"] += [separator_id] + features[idx]["input_ids"][1:]
if self.return_position_ids:
ret["position_ids"] += list(range(len(features[idx]["input_ids"])))
return default_data_collator([ret], return_tensors)