1569 lines
76 KiB
Python
1569 lines
76 KiB
Python
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# Copyright 2020 The HuggingFace Team. All rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import random
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import warnings
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from collections.abc import Mapping
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from dataclasses import dataclass
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from random import randint
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from typing import Any, Callable, Dict, List, NewType, Optional, Tuple, Union
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import numpy as np
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from ..models.bert import BertTokenizer, BertTokenizerFast
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from ..tokenization_utils_base import PreTrainedTokenizerBase
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from ..utils import PaddingStrategy
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InputDataClass = NewType("InputDataClass", Any)
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"""
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A DataCollator is a function that takes a list of samples from a Dataset and collate them into a batch, as a dictionary
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of PyTorch/TensorFlow tensors or NumPy arrays.
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"""
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DataCollator = NewType("DataCollator", Callable[[List[InputDataClass]], Dict[str, Any]])
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class DataCollatorMixin:
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def __call__(self, features, return_tensors=None):
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if return_tensors is None:
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return_tensors = self.return_tensors
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if return_tensors == "tf":
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return self.tf_call(features)
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elif return_tensors == "pt":
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return self.torch_call(features)
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elif return_tensors == "np":
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return self.numpy_call(features)
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else:
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raise ValueError(f"Framework '{return_tensors}' not recognized!")
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def pad_without_fast_tokenizer_warning(tokenizer, *pad_args, **pad_kwargs):
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"""
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Pads without triggering the warning about how using the pad function is sub-optimal when using a fast tokenizer.
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"""
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# To avoid errors when using Feature extractors
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if not hasattr(tokenizer, "deprecation_warnings"):
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return tokenizer.pad(*pad_args, **pad_kwargs)
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# Save the state of the warning, then disable it
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warning_state = tokenizer.deprecation_warnings.get("Asking-to-pad-a-fast-tokenizer", False)
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tokenizer.deprecation_warnings["Asking-to-pad-a-fast-tokenizer"] = True
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try:
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padded = tokenizer.pad(*pad_args, **pad_kwargs)
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finally:
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# Restore the state of the warning.
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tokenizer.deprecation_warnings["Asking-to-pad-a-fast-tokenizer"] = warning_state
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return padded
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def default_data_collator(features: List[InputDataClass], return_tensors="pt") -> Dict[str, Any]:
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"""
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Very simple data collator that simply collates batches of dict-like objects and performs special handling for
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potential keys named:
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- `label`: handles a single value (int or float) per object
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- `label_ids`: handles a list of values per object
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Does not do any additional preprocessing: property names of the input object will be used as corresponding inputs
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to the model. See glue and ner for example of how it's useful.
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"""
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# In this function we'll make the assumption that all `features` in the batch
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# have the same attributes.
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# So we will look at the first element as a proxy for what attributes exist
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# on the whole batch.
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if return_tensors == "pt":
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return torch_default_data_collator(features)
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elif return_tensors == "tf":
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return tf_default_data_collator(features)
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elif return_tensors == "np":
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return numpy_default_data_collator(features)
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@dataclass
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class DefaultDataCollator(DataCollatorMixin):
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"""
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Very simple data collator that simply collates batches of dict-like objects and performs special handling for
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potential keys named:
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- `label`: handles a single value (int or float) per object
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- `label_ids`: handles a list of values per object
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Does not do any additional preprocessing: property names of the input object will be used as corresponding inputs
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to the model. See glue and ner for example of how it's useful.
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This is an object (like other data collators) rather than a pure function like default_data_collator. This can be
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helpful if you need to set a return_tensors value at initialization.
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Args:
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return_tensors (`str`, *optional*, defaults to `"pt"`):
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The type of Tensor to return. Allowable values are "np", "pt" and "tf".
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"""
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return_tensors: str = "pt"
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def __call__(self, features: List[Dict[str, Any]], return_tensors=None) -> Dict[str, Any]:
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if return_tensors is None:
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return_tensors = self.return_tensors
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return default_data_collator(features, return_tensors)
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def torch_default_data_collator(features: List[InputDataClass]) -> Dict[str, Any]:
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import torch
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if not isinstance(features[0], Mapping):
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features = [vars(f) for f in features]
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first = features[0]
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batch = {}
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# Special handling for labels.
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# Ensure that tensor is created with the correct type
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# (it should be automatically the case, but let's make sure of it.)
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if "label" in first and first["label"] is not None:
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label = first["label"].item() if isinstance(first["label"], torch.Tensor) else first["label"]
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dtype = torch.long if isinstance(label, int) else torch.float
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batch["labels"] = torch.tensor([f["label"] for f in features], dtype=dtype)
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elif "label_ids" in first and first["label_ids"] is not None:
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if isinstance(first["label_ids"], torch.Tensor):
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batch["labels"] = torch.stack([f["label_ids"] for f in features])
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else:
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dtype = torch.long if isinstance(first["label_ids"][0], int) else torch.float
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batch["labels"] = torch.tensor([f["label_ids"] for f in features], dtype=dtype)
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# Handling of all other possible keys.
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# Again, we will use the first element to figure out which key/values are not None for this model.
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for k, v in first.items():
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if k not in ("label", "label_ids") and v is not None and not isinstance(v, str):
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if isinstance(v, torch.Tensor):
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batch[k] = torch.stack([f[k] for f in features])
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elif isinstance(v, np.ndarray):
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batch[k] = torch.tensor(np.stack([f[k] for f in features]))
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else:
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batch[k] = torch.tensor([f[k] for f in features])
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return batch
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def tf_default_data_collator(features: List[InputDataClass]) -> Dict[str, Any]:
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import tensorflow as tf
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if not isinstance(features[0], Mapping):
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features = [vars(f) for f in features]
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first = features[0]
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batch = {}
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# Special handling for labels.
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# Ensure that tensor is created with the correct type
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# (it should be automatically the case, but let's make sure of it.)
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if "label" in first and first["label"] is not None:
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label_col_name = "label"
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elif "label_ids" in first and first["label_ids"] is not None:
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label_col_name = "label_ids"
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elif "labels" in first and first["labels"] is not None:
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label_col_name = "labels"
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else:
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label_col_name = None
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if label_col_name is not None:
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if isinstance(first[label_col_name], tf.Tensor):
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dtype = tf.int64 if first[label_col_name].dtype.is_integer else tf.float32
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elif isinstance(first[label_col_name], np.ndarray) or isinstance(first[label_col_name], np.generic):
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dtype = tf.int64 if np.issubdtype(first[label_col_name].dtype, np.integer) else tf.float32
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elif isinstance(first[label_col_name], (tuple, list)):
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dtype = tf.int64 if isinstance(first[label_col_name][0], int) else tf.float32
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else:
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dtype = tf.int64 if isinstance(first[label_col_name], int) else tf.float32
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batch["labels"] = tf.convert_to_tensor([f[label_col_name] for f in features], dtype=dtype)
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# Handling of all other possible keys.
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# Again, we will use the first element to figure out which key/values are not None for this model.
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for k, v in first.items():
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if k not in ("label", "label_ids", "labels") and v is not None and not isinstance(v, str):
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if isinstance(v, (tf.Tensor, np.ndarray)):
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batch[k] = tf.stack([f[k] for f in features])
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else:
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batch[k] = tf.convert_to_tensor([f[k] for f in features])
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return batch
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def numpy_default_data_collator(features: List[InputDataClass]) -> Dict[str, Any]:
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if not isinstance(features[0], Mapping):
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features = [vars(f) for f in features]
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first = features[0]
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batch = {}
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# Special handling for labels.
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# Ensure that tensor is created with the correct type
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# (it should be automatically the case, but let's make sure of it.)
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if "label" in first and first["label"] is not None:
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label = first["label"].item() if isinstance(first["label"], np.ndarray) else first["label"]
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dtype = np.int64 if isinstance(label, int) else np.float32
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batch["labels"] = np.array([f["label"] for f in features], dtype=dtype)
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elif "label_ids" in first and first["label_ids"] is not None:
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if isinstance(first["label_ids"], np.ndarray):
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batch["labels"] = np.stack([f["label_ids"] for f in features])
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else:
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dtype = np.int64 if isinstance(first["label_ids"][0], int) else np.float32
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batch["labels"] = np.array([f["label_ids"] for f in features], dtype=dtype)
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# Handling of all other possible keys.
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# Again, we will use the first element to figure out which key/values are not None for this model.
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for k, v in first.items():
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if k not in ("label", "label_ids") and v is not None and not isinstance(v, str):
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if isinstance(v, np.ndarray):
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batch[k] = np.stack([f[k] for f in features])
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else:
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batch[k] = np.array([f[k] for f in features])
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return batch
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@dataclass
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class DataCollatorWithPadding:
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"""
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Data collator that will dynamically pad the inputs received.
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Args:
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tokenizer ([`PreTrainedTokenizer`] or [`PreTrainedTokenizerFast`]):
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The tokenizer used for encoding the data.
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padding (`bool`, `str` or [`~utils.PaddingStrategy`], *optional*, defaults to `True`):
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Select a strategy to pad the returned sequences (according to the model's padding side and padding index)
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among:
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- `True` or `'longest'` (default): Pad to the longest sequence in the batch (or no padding if only a single
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sequence is provided).
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- `'max_length'`: Pad to a maximum length specified with the argument `max_length` or to the maximum
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acceptable input length for the model if that argument is not provided.
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- `False` or `'do_not_pad'`: No padding (i.e., can output a batch with sequences of different lengths).
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max_length (`int`, *optional*):
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Maximum length of the returned list and optionally padding length (see above).
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pad_to_multiple_of (`int`, *optional*):
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If set will pad the sequence to a multiple of the provided value.
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This is especially useful to enable the use of Tensor Cores on NVIDIA hardware with compute capability >=
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7.5 (Volta).
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return_tensors (`str`, *optional*, defaults to `"pt"`):
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The type of Tensor to return. Allowable values are "np", "pt" and "tf".
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"""
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tokenizer: PreTrainedTokenizerBase
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padding: Union[bool, str, PaddingStrategy] = True
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max_length: Optional[int] = None
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pad_to_multiple_of: Optional[int] = None
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return_tensors: str = "pt"
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def __call__(self, features: List[Dict[str, Any]]) -> Dict[str, Any]:
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batch = pad_without_fast_tokenizer_warning(
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self.tokenizer,
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features,
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padding=self.padding,
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max_length=self.max_length,
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pad_to_multiple_of=self.pad_to_multiple_of,
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return_tensors=self.return_tensors,
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)
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if "label" in batch:
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batch["labels"] = batch["label"]
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del batch["label"]
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if "label_ids" in batch:
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batch["labels"] = batch["label_ids"]
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del batch["label_ids"]
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return batch
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@dataclass
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class DataCollatorForTokenClassification(DataCollatorMixin):
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"""
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Data collator that will dynamically pad the inputs received, as well as the labels.
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Args:
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tokenizer ([`PreTrainedTokenizer`] or [`PreTrainedTokenizerFast`]):
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The tokenizer used for encoding the data.
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padding (`bool`, `str` or [`~utils.PaddingStrategy`], *optional*, defaults to `True`):
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Select a strategy to pad the returned sequences (according to the model's padding side and padding index)
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among:
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- `True` or `'longest'` (default): Pad to the longest sequence in the batch (or no padding if only a single
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sequence is provided).
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- `'max_length'`: Pad to a maximum length specified with the argument `max_length` or to the maximum
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acceptable input length for the model if that argument is not provided.
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- `False` or `'do_not_pad'`: No padding (i.e., can output a batch with sequences of different lengths).
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max_length (`int`, *optional*):
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Maximum length of the returned list and optionally padding length (see above).
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pad_to_multiple_of (`int`, *optional*):
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If set will pad the sequence to a multiple of the provided value.
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This is especially useful to enable the use of Tensor Cores on NVIDIA hardware with compute capability >=
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7.5 (Volta).
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label_pad_token_id (`int`, *optional*, defaults to -100):
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The id to use when padding the labels (-100 will be automatically ignore by PyTorch loss functions).
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return_tensors (`str`, *optional*, defaults to `"pt"`):
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The type of Tensor to return. Allowable values are "np", "pt" and "tf".
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"""
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tokenizer: PreTrainedTokenizerBase
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padding: Union[bool, str, PaddingStrategy] = True
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max_length: Optional[int] = None
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pad_to_multiple_of: Optional[int] = None
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label_pad_token_id: int = -100
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return_tensors: str = "pt"
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def torch_call(self, features):
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import torch
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label_name = "label" if "label" in features[0].keys() else "labels"
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labels = [feature[label_name] for feature in features] if label_name in features[0].keys() else None
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no_labels_features = [{k: v for k, v in feature.items() if k != label_name} for feature in features]
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batch = pad_without_fast_tokenizer_warning(
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self.tokenizer,
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no_labels_features,
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padding=self.padding,
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max_length=self.max_length,
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pad_to_multiple_of=self.pad_to_multiple_of,
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return_tensors="pt",
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)
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if labels is None:
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return batch
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sequence_length = batch["input_ids"].shape[1]
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padding_side = self.tokenizer.padding_side
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def to_list(tensor_or_iterable):
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if isinstance(tensor_or_iterable, torch.Tensor):
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return tensor_or_iterable.tolist()
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return list(tensor_or_iterable)
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if padding_side == "right":
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batch[label_name] = [
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to_list(label) + [self.label_pad_token_id] * (sequence_length - len(label)) for label in labels
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]
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else:
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batch[label_name] = [
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[self.label_pad_token_id] * (sequence_length - len(label)) + to_list(label) for label in labels
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]
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batch[label_name] = torch.tensor(batch[label_name], dtype=torch.int64)
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return batch
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def tf_call(self, features):
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import tensorflow as tf
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label_name = "label" if "label" in features[0].keys() else "labels"
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labels = [feature[label_name] for feature in features] if label_name in features[0].keys() else None
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batch = pad_without_fast_tokenizer_warning(
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self.tokenizer,
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features,
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padding=self.padding,
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max_length=self.max_length,
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pad_to_multiple_of=self.pad_to_multiple_of,
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# Conversion to tensors will fail if we have labels as they are not of the same length yet.
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return_tensors="tf" if labels is None else None,
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)
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if labels is None:
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return batch
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sequence_length = tf.convert_to_tensor(batch["input_ids"]).shape[1]
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padding_side = self.tokenizer.padding_side
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if padding_side == "right":
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batch["labels"] = [
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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):
|
||
|
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
|
||
|
labels = [feature["labels"] for feature in features] if "labels" in features[0].keys() else None
|
||
|
# We have to pad the labels before calling `tokenizer.pad` as this method won't pad them and needs them of the
|
||
|
# same length to return tensors.
|
||
|
if labels is not None:
|
||
|
max_label_length = max(len(l) for l in labels)
|
||
|
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
|
||
|
for feature in features:
|
||
|
remainder = [self.label_pad_token_id] * (max_label_length - len(feature["labels"]))
|
||
|
if isinstance(feature["labels"], list):
|
||
|
feature["labels"] = (
|
||
|
feature["labels"] + remainder if padding_side == "right" else remainder + feature["labels"]
|
||
|
)
|
||
|
elif padding_side == "right":
|
||
|
feature["labels"] = np.concatenate([feature["labels"], remainder]).astype(np.int64)
|
||
|
else:
|
||
|
feature["labels"] = np.concatenate([remainder, feature["labels"]]).astype(np.int64)
|
||
|
|
||
|
features = 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=return_tensors,
|
||
|
)
|
||
|
|
||
|
# 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=features["labels"])
|
||
|
features["decoder_input_ids"] = decoder_input_ids
|
||
|
|
||
|
return features
|
||
|
|
||
|
|
||
|
@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".
|
||
|
|
||
|
<Tip>
|
||
|
|
||
|
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`.
|
||
|
|
||
|
</Tip>"""
|
||
|
|
||
|
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, 0.1) & 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
|
||
|
|
||
|
<Tip>
|
||
|
|
||
|
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`].
|
||
|
|
||
|
</Tip>"""
|
||
|
|
||
|
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)
|