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create_pretraining_data.py
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# Copyright 2024 The TensorFlow Authors. 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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"""Create masked LM/next sentence masked_lm TF examples for BERT."""
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import collections
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import itertools
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import random
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# Import libraries
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from absl import app
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from absl import flags
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from absl import logging
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import tensorflow as tf, tf_keras
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from official.nlp.tools import tokenization
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FLAGS = flags.FLAGS
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flags.DEFINE_string("input_file", None,
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"Input raw text file (or comma-separated list of files).")
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flags.DEFINE_string(
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"output_file", None,
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"Output TF example file (or comma-separated list of files).")
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flags.DEFINE_enum(
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"tokenization",
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"WordPiece",
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["WordPiece", "SentencePiece"],
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"Specifies the tokenizer implementation, i.e., whether to use WordPiece "
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"or SentencePiece tokenizer. Canonical BERT uses WordPiece tokenizer, "
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"while ALBERT uses SentencePiece tokenizer.",
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)
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flags.DEFINE_string(
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"vocab_file",
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None,
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"For WordPiece tokenization, the vocabulary file of the tokenizer.",
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)
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flags.DEFINE_string(
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"sp_model_file",
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"",
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"For SentencePiece tokenization, the path to the model of the tokenizer.",
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)
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flags.DEFINE_bool(
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"do_lower_case", True,
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"Whether to lower case the input text. Should be True for uncased "
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"models and False for cased models.")
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flags.DEFINE_bool(
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"do_whole_word_mask",
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False,
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"Whether to use whole word masking rather than per-token masking.",
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)
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flags.DEFINE_integer(
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"max_ngram_size", None,
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"Mask contiguous whole words (n-grams) of up to `max_ngram_size` using a "
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"weighting scheme to favor shorter n-grams. "
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"Note: `--do_whole_word_mask=True` must also be set when n-gram masking.")
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flags.DEFINE_bool(
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"gzip_compress", False,
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"Whether to use `GZIP` compress option to get compressed TFRecord files.")
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flags.DEFINE_bool(
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"use_v2_feature_names", False,
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"Whether to use the feature names consistent with the models.")
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flags.DEFINE_integer("max_seq_length", 128, "Maximum sequence length.")
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flags.DEFINE_integer("max_predictions_per_seq", 20,
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"Maximum number of masked LM predictions per sequence.")
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flags.DEFINE_integer("random_seed", 12345, "Random seed for data generation.")
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flags.DEFINE_integer(
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"dupe_factor", 10,
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"Number of times to duplicate the input data (with different masks).")
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flags.DEFINE_float("masked_lm_prob", 0.15, "Masked LM probability.")
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flags.DEFINE_float(
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"short_seq_prob", 0.1,
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"Probability of creating sequences which are shorter than the "
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"maximum length.")
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class TrainingInstance(object):
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"""A single training instance (sentence pair)."""
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def __init__(self, tokens, segment_ids, masked_lm_positions, masked_lm_labels,
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is_random_next):
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self.tokens = tokens
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self.segment_ids = segment_ids
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self.is_random_next = is_random_next
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self.masked_lm_positions = masked_lm_positions
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self.masked_lm_labels = masked_lm_labels
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def __str__(self):
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s = ""
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s += "tokens: %s\n" % (" ".join(
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[tokenization.printable_text(x) for x in self.tokens]))
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s += "segment_ids: %s\n" % (" ".join([str(x) for x in self.segment_ids]))
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s += "is_random_next: %s\n" % self.is_random_next
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s += "masked_lm_positions: %s\n" % (" ".join(
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[str(x) for x in self.masked_lm_positions]))
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s += "masked_lm_labels: %s\n" % (" ".join(
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[tokenization.printable_text(x) for x in self.masked_lm_labels]))
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s += "\n"
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return s
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def __repr__(self):
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return self.__str__()
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def write_instance_to_example_files(instances, tokenizer, max_seq_length,
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max_predictions_per_seq, output_files,
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gzip_compress, use_v2_feature_names):
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"""Creates TF example files from `TrainingInstance`s."""
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writers = []
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for output_file in output_files:
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writers.append(
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tf.io.TFRecordWriter(
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output_file, options="GZIP" if gzip_compress else ""))
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writer_index = 0
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total_written = 0
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for (inst_index, instance) in enumerate(instances):
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input_ids = tokenizer.convert_tokens_to_ids(instance.tokens)
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input_mask = [1] * len(input_ids)
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segment_ids = list(instance.segment_ids)
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assert len(input_ids) <= max_seq_length
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while len(input_ids) < max_seq_length:
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input_ids.append(0)
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input_mask.append(0)
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segment_ids.append(0)
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assert len(input_ids) == max_seq_length
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assert len(input_mask) == max_seq_length
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assert len(segment_ids) == max_seq_length
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masked_lm_positions = list(instance.masked_lm_positions)
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masked_lm_ids = tokenizer.convert_tokens_to_ids(instance.masked_lm_labels)
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masked_lm_weights = [1.0] * len(masked_lm_ids)
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while len(masked_lm_positions) < max_predictions_per_seq:
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masked_lm_positions.append(0)
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masked_lm_ids.append(0)
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masked_lm_weights.append(0.0)
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next_sentence_label = 1 if instance.is_random_next else 0
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features = collections.OrderedDict()
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if use_v2_feature_names:
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features["input_word_ids"] = create_int_feature(input_ids)
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features["input_type_ids"] = create_int_feature(segment_ids)
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else:
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features["input_ids"] = create_int_feature(input_ids)
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features["segment_ids"] = create_int_feature(segment_ids)
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features["input_mask"] = create_int_feature(input_mask)
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features["masked_lm_positions"] = create_int_feature(masked_lm_positions)
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features["masked_lm_ids"] = create_int_feature(masked_lm_ids)
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features["masked_lm_weights"] = create_float_feature(masked_lm_weights)
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features["next_sentence_labels"] = create_int_feature([next_sentence_label])
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tf_example = tf.train.Example(features=tf.train.Features(feature=features))
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writers[writer_index].write(tf_example.SerializeToString())
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writer_index = (writer_index + 1) % len(writers)
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total_written += 1
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if inst_index < 20:
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logging.info("*** Example ***")
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logging.info("tokens: %s", " ".join(
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[tokenization.printable_text(x) for x in instance.tokens]))
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for feature_name in features.keys():
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feature = features[feature_name]
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values = []
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if feature.int64_list.value:
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values = feature.int64_list.value
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elif feature.float_list.value:
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values = feature.float_list.value
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logging.info("%s: %s", feature_name, " ".join([str(x) for x in values]))
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for writer in writers:
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writer.close()
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logging.info("Wrote %d total instances", total_written)
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def create_int_feature(values):
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feature = tf.train.Feature(int64_list=tf.train.Int64List(value=list(values)))
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return feature
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def create_float_feature(values):
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feature = tf.train.Feature(float_list=tf.train.FloatList(value=list(values)))
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return feature
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def create_training_instances(
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input_files,
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tokenizer,
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processor_text_fn,
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max_seq_length,
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dupe_factor,
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short_seq_prob,
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masked_lm_prob,
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max_predictions_per_seq,
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rng,
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do_whole_word_mask=False,
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max_ngram_size=None,
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):
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"""Create `TrainingInstance`s from raw text."""
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all_documents = [[]]
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# Input file format:
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# (1) One sentence per line. These should ideally be actual sentences, not
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# entire paragraphs or arbitrary spans of text. (Because we use the
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# sentence boundaries for the "next sentence prediction" task).
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# (2) Blank lines between documents. Document boundaries are needed so
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# that the "next sentence prediction" task doesn't span between documents.
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for input_file in input_files:
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with tf.io.gfile.GFile(input_file, "rb") as reader:
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for line in reader:
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line = processor_text_fn(line)
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# Empty lines are used as document delimiters
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if not line:
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all_documents.append([])
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tokens = tokenizer.tokenize(line)
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if tokens:
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all_documents[-1].append(tokens)
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# Remove empty documents
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all_documents = [x for x in all_documents if x]
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rng.shuffle(all_documents)
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vocab_words = list(tokenizer.vocab.keys())
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instances = []
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for _ in range(dupe_factor):
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for document_index in range(len(all_documents)):
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instances.extend(
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create_instances_from_document(
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all_documents, document_index, max_seq_length, short_seq_prob,
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masked_lm_prob, max_predictions_per_seq, vocab_words, rng,
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do_whole_word_mask, max_ngram_size))
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rng.shuffle(instances)
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return instances
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def create_instances_from_document(
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all_documents, document_index, max_seq_length, short_seq_prob,
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masked_lm_prob, max_predictions_per_seq, vocab_words, rng,
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do_whole_word_mask=False,
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max_ngram_size=None):
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"""Creates `TrainingInstance`s for a single document."""
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document = all_documents[document_index]
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# Account for [CLS], [SEP], [SEP]
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max_num_tokens = max_seq_length - 3
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# We *usually* want to fill up the entire sequence since we are padding
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# to `max_seq_length` anyways, so short sequences are generally wasted
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# computation. However, we *sometimes*
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# (i.e., short_seq_prob == 0.1 == 10% of the time) want to use shorter
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# sequences to minimize the mismatch between pre-training and fine-tuning.
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# The `target_seq_length` is just a rough target however, whereas
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# `max_seq_length` is a hard limit.
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target_seq_length = max_num_tokens
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if rng.random() < short_seq_prob:
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target_seq_length = rng.randint(2, max_num_tokens)
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# We DON'T just concatenate all of the tokens from a document into a long
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# sequence and choose an arbitrary split point because this would make the
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# next sentence prediction task too easy. Instead, we split the input into
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# segments "A" and "B" based on the actual "sentences" provided by the user
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# input.
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instances = []
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current_chunk = []
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current_length = 0
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i = 0
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while i < len(document):
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segment = document[i]
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current_chunk.append(segment)
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current_length += len(segment)
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if i == len(document) - 1 or current_length >= target_seq_length:
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if current_chunk:
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# `a_end` is how many segments from `current_chunk` go into the `A`
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# (first) sentence.
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a_end = 1
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if len(current_chunk) >= 2:
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a_end = rng.randint(1, len(current_chunk) - 1)
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tokens_a = []
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for j in range(a_end):
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tokens_a.extend(current_chunk[j])
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tokens_b = []
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# Random next
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is_random_next = False
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if len(current_chunk) == 1 or rng.random() < 0.5:
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is_random_next = True
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target_b_length = target_seq_length - len(tokens_a)
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# This should rarely go for more than one iteration for large
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# corpora. However, just to be careful, we try to make sure that
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# the random document is not the same as the document
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# we're processing.
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for _ in range(10):
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random_document_index = rng.randint(0, len(all_documents) - 1)
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if random_document_index != document_index:
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break
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random_document = all_documents[random_document_index]
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random_start = rng.randint(0, len(random_document) - 1)
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for j in range(random_start, len(random_document)):
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tokens_b.extend(random_document[j])
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if len(tokens_b) >= target_b_length:
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break
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# We didn't actually use these segments so we "put them back" so
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# they don't go to waste.
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num_unused_segments = len(current_chunk) - a_end
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i -= num_unused_segments
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# Actual next
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else:
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is_random_next = False
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for j in range(a_end, len(current_chunk)):
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tokens_b.extend(current_chunk[j])
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truncate_seq_pair(tokens_a, tokens_b, max_num_tokens, rng)
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assert len(tokens_a) >= 1
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assert len(tokens_b) >= 1
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tokens = []
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segment_ids = []
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tokens.append("[CLS]")
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segment_ids.append(0)
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for token in tokens_a:
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tokens.append(token)
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segment_ids.append(0)
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tokens.append("[SEP]")
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segment_ids.append(0)
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for token in tokens_b:
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tokens.append(token)
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segment_ids.append(1)
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tokens.append("[SEP]")
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segment_ids.append(1)
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(tokens, masked_lm_positions,
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masked_lm_labels) = create_masked_lm_predictions(
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| 376 |
-
tokens, masked_lm_prob, max_predictions_per_seq, vocab_words, rng,
|
| 377 |
-
do_whole_word_mask, max_ngram_size)
|
| 378 |
-
instance = TrainingInstance(
|
| 379 |
-
tokens=tokens,
|
| 380 |
-
segment_ids=segment_ids,
|
| 381 |
-
is_random_next=is_random_next,
|
| 382 |
-
masked_lm_positions=masked_lm_positions,
|
| 383 |
-
masked_lm_labels=masked_lm_labels)
|
| 384 |
-
instances.append(instance)
|
| 385 |
-
current_chunk = []
|
| 386 |
-
current_length = 0
|
| 387 |
-
i += 1
|
| 388 |
-
|
| 389 |
-
return instances
|
| 390 |
-
|
| 391 |
-
|
| 392 |
-
MaskedLmInstance = collections.namedtuple("MaskedLmInstance",
|
| 393 |
-
["index", "label"])
|
| 394 |
-
|
| 395 |
-
# A _Gram is a [half-open) interval of token indices which form a word.
|
| 396 |
-
# E.g.,
|
| 397 |
-
# words: ["The", "doghouse"]
|
| 398 |
-
# tokens: ["The", "dog", "##house"]
|
| 399 |
-
# grams: [(0,1), (1,3)]
|
| 400 |
-
_Gram = collections.namedtuple("_Gram", ["begin", "end"])
|
| 401 |
-
|
| 402 |
-
|
| 403 |
-
def _window(iterable, size):
|
| 404 |
-
"""Helper to create a sliding window iterator with a given size.
|
| 405 |
-
|
| 406 |
-
E.g.,
|
| 407 |
-
input = [1, 2, 3, 4]
|
| 408 |
-
_window(input, 1) => [1], [2], [3], [4]
|
| 409 |
-
_window(input, 2) => [1, 2], [2, 3], [3, 4]
|
| 410 |
-
_window(input, 3) => [1, 2, 3], [2, 3, 4]
|
| 411 |
-
_window(input, 4) => [1, 2, 3, 4]
|
| 412 |
-
_window(input, 5) => None
|
| 413 |
-
|
| 414 |
-
Args:
|
| 415 |
-
iterable: elements to iterate over.
|
| 416 |
-
size: size of the window.
|
| 417 |
-
|
| 418 |
-
Yields:
|
| 419 |
-
Elements of `iterable` batched into a sliding window of length `size`.
|
| 420 |
-
"""
|
| 421 |
-
i = iter(iterable)
|
| 422 |
-
window = []
|
| 423 |
-
try:
|
| 424 |
-
for e in range(0, size):
|
| 425 |
-
window.append(next(i))
|
| 426 |
-
yield window
|
| 427 |
-
except StopIteration:
|
| 428 |
-
# handle the case where iterable's length is less than the window size.
|
| 429 |
-
return
|
| 430 |
-
for e in i:
|
| 431 |
-
window = window[1:] + [e]
|
| 432 |
-
yield window
|
| 433 |
-
|
| 434 |
-
|
| 435 |
-
def _contiguous(sorted_grams):
|
| 436 |
-
"""Test whether a sequence of grams is contiguous.
|
| 437 |
-
|
| 438 |
-
Args:
|
| 439 |
-
sorted_grams: _Grams which are sorted in increasing order.
|
| 440 |
-
Returns:
|
| 441 |
-
True if `sorted_grams` are touching each other.
|
| 442 |
-
|
| 443 |
-
E.g.,
|
| 444 |
-
_contiguous([(1, 4), (4, 5), (5, 10)]) == True
|
| 445 |
-
_contiguous([(1, 2), (4, 5)]) == False
|
| 446 |
-
"""
|
| 447 |
-
for a, b in _window(sorted_grams, 2):
|
| 448 |
-
if a.end != b.begin:
|
| 449 |
-
return False
|
| 450 |
-
return True
|
| 451 |
-
|
| 452 |
-
|
| 453 |
-
def _masking_ngrams(grams, max_ngram_size, max_masked_tokens, rng):
|
| 454 |
-
"""Create a list of masking {1, ..., n}-grams from a list of one-grams.
|
| 455 |
-
|
| 456 |
-
This is an extension of 'whole word masking' to mask multiple, contiguous
|
| 457 |
-
words such as (e.g., "the red boat").
|
| 458 |
-
|
| 459 |
-
Each input gram represents the token indices of a single word,
|
| 460 |
-
words: ["the", "red", "boat"]
|
| 461 |
-
tokens: ["the", "red", "boa", "##t"]
|
| 462 |
-
grams: [(0,1), (1,2), (2,4)]
|
| 463 |
-
|
| 464 |
-
For a `max_ngram_size` of three, possible outputs masks include:
|
| 465 |
-
1-grams: (0,1), (1,2), (2,4)
|
| 466 |
-
2-grams: (0,2), (1,4)
|
| 467 |
-
3-grams; (0,4)
|
| 468 |
-
|
| 469 |
-
Output masks will not overlap and contain less than `max_masked_tokens` total
|
| 470 |
-
tokens. E.g., for the example above with `max_masked_tokens` as three,
|
| 471 |
-
valid outputs are,
|
| 472 |
-
[(0,1), (1,2)] # "the", "red" covering two tokens
|
| 473 |
-
[(1,2), (2,4)] # "red", "boa", "##t" covering three tokens
|
| 474 |
-
|
| 475 |
-
The length of the selected n-gram follows a zipf weighting to
|
| 476 |
-
favor shorter n-gram sizes (weight(1)=1, weight(2)=1/2, weight(3)=1/3, ...).
|
| 477 |
-
|
| 478 |
-
Args:
|
| 479 |
-
grams: List of one-grams.
|
| 480 |
-
max_ngram_size: Maximum number of contiguous one-grams combined to create
|
| 481 |
-
an n-gram.
|
| 482 |
-
max_masked_tokens: Maximum total number of tokens to be masked.
|
| 483 |
-
rng: `random.Random` generator.
|
| 484 |
-
|
| 485 |
-
Returns:
|
| 486 |
-
A list of n-grams to be used as masks.
|
| 487 |
-
"""
|
| 488 |
-
if not grams:
|
| 489 |
-
return None
|
| 490 |
-
|
| 491 |
-
grams = sorted(grams)
|
| 492 |
-
num_tokens = grams[-1].end
|
| 493 |
-
|
| 494 |
-
# Ensure our grams are valid (i.e., they don't overlap).
|
| 495 |
-
for a, b in _window(grams, 2):
|
| 496 |
-
if a.end > b.begin:
|
| 497 |
-
raise ValueError("overlapping grams: {}".format(grams))
|
| 498 |
-
|
| 499 |
-
# Build map from n-gram length to list of n-grams.
|
| 500 |
-
ngrams = {i: [] for i in range(1, max_ngram_size+1)}
|
| 501 |
-
for gram_size in range(1, max_ngram_size+1):
|
| 502 |
-
for g in _window(grams, gram_size):
|
| 503 |
-
if _contiguous(g):
|
| 504 |
-
# Add an n-gram which spans these one-grams.
|
| 505 |
-
ngrams[gram_size].append(_Gram(g[0].begin, g[-1].end))
|
| 506 |
-
|
| 507 |
-
# Shuffle each list of n-grams.
|
| 508 |
-
for v in ngrams.values():
|
| 509 |
-
rng.shuffle(v)
|
| 510 |
-
|
| 511 |
-
# Create the weighting for n-gram length selection.
|
| 512 |
-
# Stored cumulatively for `random.choices` below.
|
| 513 |
-
cummulative_weights = list(
|
| 514 |
-
itertools.accumulate([1./n for n in range(1, max_ngram_size+1)]))
|
| 515 |
-
|
| 516 |
-
output_ngrams = []
|
| 517 |
-
# Keep a bitmask of which tokens have been masked.
|
| 518 |
-
masked_tokens = [False] * num_tokens
|
| 519 |
-
# Loop until we have enough masked tokens or there are no more candidate
|
| 520 |
-
# n-grams of any length.
|
| 521 |
-
# Each code path should ensure one or more elements from `ngrams` are removed
|
| 522 |
-
# to guarantee this loop terminates.
|
| 523 |
-
while (sum(masked_tokens) < max_masked_tokens and
|
| 524 |
-
sum(len(s) for s in ngrams.values())):
|
| 525 |
-
# Pick an n-gram size based on our weights.
|
| 526 |
-
sz = random.choices(range(1, max_ngram_size+1),
|
| 527 |
-
cum_weights=cummulative_weights)[0]
|
| 528 |
-
|
| 529 |
-
# Ensure this size doesn't result in too many masked tokens.
|
| 530 |
-
# E.g., a two-gram contains _at least_ two tokens.
|
| 531 |
-
if sum(masked_tokens) + sz > max_masked_tokens:
|
| 532 |
-
# All n-grams of this length are too long and can be removed from
|
| 533 |
-
# consideration.
|
| 534 |
-
ngrams[sz].clear()
|
| 535 |
-
continue
|
| 536 |
-
|
| 537 |
-
# All of the n-grams of this size have been used.
|
| 538 |
-
if not ngrams[sz]:
|
| 539 |
-
continue
|
| 540 |
-
|
| 541 |
-
# Choose a random n-gram of the given size.
|
| 542 |
-
gram = ngrams[sz].pop()
|
| 543 |
-
num_gram_tokens = gram.end-gram.begin
|
| 544 |
-
|
| 545 |
-
# Check if this would add too many tokens.
|
| 546 |
-
if num_gram_tokens + sum(masked_tokens) > max_masked_tokens:
|
| 547 |
-
continue
|
| 548 |
-
|
| 549 |
-
# Check if any of the tokens in this gram have already been masked.
|
| 550 |
-
if sum(masked_tokens[gram.begin:gram.end]):
|
| 551 |
-
continue
|
| 552 |
-
|
| 553 |
-
# Found a usable n-gram! Mark its tokens as masked and add it to return.
|
| 554 |
-
masked_tokens[gram.begin:gram.end] = [True] * (gram.end-gram.begin)
|
| 555 |
-
output_ngrams.append(gram)
|
| 556 |
-
return output_ngrams
|
| 557 |
-
|
| 558 |
-
|
| 559 |
-
def _tokens_to_grams(tokens):
|
| 560 |
-
"""Reconstitue grams (words) from `tokens`.
|
| 561 |
-
|
| 562 |
-
E.g.,
|
| 563 |
-
tokens: ['[CLS]', 'That', 'lit', '##tle', 'blue', 'tru', '##ck', '[SEP]']
|
| 564 |
-
grams: [ [1,2), [2, 4), [4,5) , [5, 6)]
|
| 565 |
-
|
| 566 |
-
Args:
|
| 567 |
-
tokens: list of tokens (word pieces or sentence pieces).
|
| 568 |
-
|
| 569 |
-
Returns:
|
| 570 |
-
List of _Grams representing spans of whole words
|
| 571 |
-
(without "[CLS]" and "[SEP]").
|
| 572 |
-
"""
|
| 573 |
-
grams = []
|
| 574 |
-
gram_start_pos = None
|
| 575 |
-
for i, token in enumerate(tokens):
|
| 576 |
-
if gram_start_pos is not None and token.startswith("##"):
|
| 577 |
-
continue
|
| 578 |
-
if gram_start_pos is not None:
|
| 579 |
-
grams.append(_Gram(gram_start_pos, i))
|
| 580 |
-
if token not in ["[CLS]", "[SEP]"]:
|
| 581 |
-
gram_start_pos = i
|
| 582 |
-
else:
|
| 583 |
-
gram_start_pos = None
|
| 584 |
-
if gram_start_pos is not None:
|
| 585 |
-
grams.append(_Gram(gram_start_pos, len(tokens)))
|
| 586 |
-
return grams
|
| 587 |
-
|
| 588 |
-
|
| 589 |
-
def create_masked_lm_predictions(tokens, masked_lm_prob,
|
| 590 |
-
max_predictions_per_seq, vocab_words, rng,
|
| 591 |
-
do_whole_word_mask,
|
| 592 |
-
max_ngram_size=None):
|
| 593 |
-
"""Creates the predictions for the masked LM objective."""
|
| 594 |
-
if do_whole_word_mask:
|
| 595 |
-
grams = _tokens_to_grams(tokens)
|
| 596 |
-
else:
|
| 597 |
-
# Here we consider each token to be a word to allow for sub-word masking.
|
| 598 |
-
if max_ngram_size:
|
| 599 |
-
raise ValueError("cannot use ngram masking without whole word masking")
|
| 600 |
-
grams = [_Gram(i, i+1) for i in range(0, len(tokens))
|
| 601 |
-
if tokens[i] not in ["[CLS]", "[SEP]"]]
|
| 602 |
-
|
| 603 |
-
num_to_predict = min(max_predictions_per_seq,
|
| 604 |
-
max(1, int(round(len(tokens) * masked_lm_prob))))
|
| 605 |
-
# Generate masks. If `max_ngram_size` in [0, None] it means we're doing
|
| 606 |
-
# whole word masking or token level masking. Both of these can be treated
|
| 607 |
-
# as the `max_ngram_size=1` case.
|
| 608 |
-
masked_grams = _masking_ngrams(grams, max_ngram_size or 1,
|
| 609 |
-
num_to_predict, rng)
|
| 610 |
-
masked_lms = []
|
| 611 |
-
output_tokens = list(tokens)
|
| 612 |
-
for gram in masked_grams:
|
| 613 |
-
# 80% of the time, replace all n-gram tokens with [MASK]
|
| 614 |
-
if rng.random() < 0.8:
|
| 615 |
-
replacement_action = lambda idx: "[MASK]"
|
| 616 |
-
else:
|
| 617 |
-
# 10% of the time, keep all the original n-gram tokens.
|
| 618 |
-
if rng.random() < 0.5:
|
| 619 |
-
replacement_action = lambda idx: tokens[idx]
|
| 620 |
-
# 10% of the time, replace each n-gram token with a random word.
|
| 621 |
-
else:
|
| 622 |
-
replacement_action = lambda idx: rng.choice(vocab_words)
|
| 623 |
-
|
| 624 |
-
for idx in range(gram.begin, gram.end):
|
| 625 |
-
output_tokens[idx] = replacement_action(idx)
|
| 626 |
-
masked_lms.append(MaskedLmInstance(index=idx, label=tokens[idx]))
|
| 627 |
-
|
| 628 |
-
assert len(masked_lms) <= num_to_predict
|
| 629 |
-
masked_lms = sorted(masked_lms, key=lambda x: x.index)
|
| 630 |
-
|
| 631 |
-
masked_lm_positions = []
|
| 632 |
-
masked_lm_labels = []
|
| 633 |
-
for p in masked_lms:
|
| 634 |
-
masked_lm_positions.append(p.index)
|
| 635 |
-
masked_lm_labels.append(p.label)
|
| 636 |
-
|
| 637 |
-
return (output_tokens, masked_lm_positions, masked_lm_labels)
|
| 638 |
-
|
| 639 |
-
|
| 640 |
-
def truncate_seq_pair(tokens_a, tokens_b, max_num_tokens, rng):
|
| 641 |
-
"""Truncates a pair of sequences to a maximum sequence length."""
|
| 642 |
-
while True:
|
| 643 |
-
total_length = len(tokens_a) + len(tokens_b)
|
| 644 |
-
if total_length <= max_num_tokens:
|
| 645 |
-
break
|
| 646 |
-
|
| 647 |
-
trunc_tokens = tokens_a if len(tokens_a) > len(tokens_b) else tokens_b
|
| 648 |
-
assert len(trunc_tokens) >= 1
|
| 649 |
-
|
| 650 |
-
# We want to sometimes truncate from the front and sometimes from the
|
| 651 |
-
# back to add more randomness and avoid biases.
|
| 652 |
-
if rng.random() < 0.5:
|
| 653 |
-
del trunc_tokens[0]
|
| 654 |
-
else:
|
| 655 |
-
trunc_tokens.pop()
|
| 656 |
-
|
| 657 |
-
|
| 658 |
-
def get_processor_text_fn(is_sentence_piece, do_lower_case):
|
| 659 |
-
def processor_text_fn(text):
|
| 660 |
-
text = tokenization.convert_to_unicode(text)
|
| 661 |
-
if is_sentence_piece:
|
| 662 |
-
# Additional preprocessing specific to the SentencePiece tokenizer.
|
| 663 |
-
text = tokenization.preprocess_text(text, lower=do_lower_case)
|
| 664 |
-
|
| 665 |
-
return text.strip()
|
| 666 |
-
|
| 667 |
-
return processor_text_fn
|
| 668 |
-
|
| 669 |
-
|
| 670 |
-
def main(_):
|
| 671 |
-
if FLAGS.tokenization == "WordPiece":
|
| 672 |
-
tokenizer = tokenization.FullTokenizer(
|
| 673 |
-
vocab_file=FLAGS.vocab_file, do_lower_case=FLAGS.do_lower_case
|
| 674 |
-
)
|
| 675 |
-
processor_text_fn = get_processor_text_fn(False, FLAGS.do_lower_case)
|
| 676 |
-
else:
|
| 677 |
-
assert FLAGS.tokenization == "SentencePiece"
|
| 678 |
-
tokenizer = tokenization.FullSentencePieceTokenizer(FLAGS.sp_model_file)
|
| 679 |
-
processor_text_fn = get_processor_text_fn(True, FLAGS.do_lower_case)
|
| 680 |
-
|
| 681 |
-
input_files = []
|
| 682 |
-
for input_pattern in FLAGS.input_file.split(","):
|
| 683 |
-
input_files.extend(tf.io.gfile.glob(input_pattern))
|
| 684 |
-
|
| 685 |
-
logging.info("*** Reading from input files ***")
|
| 686 |
-
for input_file in input_files:
|
| 687 |
-
logging.info(" %s", input_file)
|
| 688 |
-
|
| 689 |
-
rng = random.Random(FLAGS.random_seed)
|
| 690 |
-
instances = create_training_instances(
|
| 691 |
-
input_files,
|
| 692 |
-
tokenizer,
|
| 693 |
-
processor_text_fn,
|
| 694 |
-
FLAGS.max_seq_length,
|
| 695 |
-
FLAGS.dupe_factor,
|
| 696 |
-
FLAGS.short_seq_prob,
|
| 697 |
-
FLAGS.masked_lm_prob,
|
| 698 |
-
FLAGS.max_predictions_per_seq,
|
| 699 |
-
rng,
|
| 700 |
-
FLAGS.do_whole_word_mask,
|
| 701 |
-
FLAGS.max_ngram_size,
|
| 702 |
-
)
|
| 703 |
-
|
| 704 |
-
output_files = FLAGS.output_file.split(",")
|
| 705 |
-
logging.info("*** Writing to output files ***")
|
| 706 |
-
for output_file in output_files:
|
| 707 |
-
logging.info(" %s", output_file)
|
| 708 |
-
|
| 709 |
-
write_instance_to_example_files(instances, tokenizer, FLAGS.max_seq_length,
|
| 710 |
-
FLAGS.max_predictions_per_seq, output_files,
|
| 711 |
-
FLAGS.gzip_compress,
|
| 712 |
-
FLAGS.use_v2_feature_names)
|
| 713 |
-
|
| 714 |
-
|
| 715 |
-
if __name__ == "__main__":
|
| 716 |
-
flags.mark_flag_as_required("input_file")
|
| 717 |
-
flags.mark_flag_as_required("output_file")
|
| 718 |
-
app.run(main)
|
|
|
|
|
|
|
|
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|
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