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+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
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+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
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+
+# Installer logs
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+.coverage.*
+.cache
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+coverage.xml
+*.cover
+.hypothesis/
+.pytest_cache/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
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+# PyBuilder
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+
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 .vscode
\ No newline at end of file

CONTRIBUTING.md

+# How to Contribute
+
+BERT needs to maintain permanent compatibility with the pre-trained model files,
+so we do not plan to make any major changes to this library (other than what was
+promised in the README). However, we can accept small patches related to
+re-factoring and documentation. To submit contributes, there are just a few
+small guidelines you need to follow.
+
+## Contributor License Agreement
+
+Contributions to this project must be accompanied by a Contributor License
+Agreement. You (or your employer) retain the copyright to your contribution;
+this simply gives us permission to use and redistribute your contributions as
+part of the project. Head over to <https://cla.developers.google.com/> to see
+your current agreements on file or to sign a new one.
+
+You generally only need to submit a CLA once, so if you've already submitted one
+(even if it was for a different project), you probably don't need to do it
+again.
+
+## Code reviews
+
+All submissions, including submissions by project members, require review. We
+use GitHub pull requests for this purpose. Consult
+[GitHub Help](https://help.github.com/articles/about-pull-requests/) for more
+information on using pull requests.
+
+## Community Guidelines
+
+This project follows
+[Google's Open Source Community Guidelines](https://opensource.google.com/conduct/).

LICENSE

+
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__init__.py

+# coding=utf-8
+# Copyright 2018 The Google AI Language Team Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+

create_pretraining_data.py

+# coding=utf-8
+# Copyright 2018 The Google AI Language Team Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Create masked LM/next sentence masked_lm TF examples for BERT."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import collections
+import random
+
+import tokenization
+import tensorflow as tf
+
+flags = tf.flags
+
+FLAGS = flags.FLAGS
+
+flags.DEFINE_string("input_file", None,
+                    "Input raw text file (or comma-separated list of files).")
+
+flags.DEFINE_string(
+    "output_file", None,
+    "Output TF example file (or comma-separated list of files).")
+
+flags.DEFINE_string("vocab_file", None,
+                    "The vocabulary file that the BERT model was trained on.")
+
+flags.DEFINE_bool(
+    "do_lower_case", True,
+    "Whether to lower case the input text. Should be True for uncased "
+    "models and False for cased models.")
+
+flags.DEFINE_integer("max_seq_length", 128, "Maximum sequence length.")
+
+flags.DEFINE_integer("max_predictions_per_seq", 20,
+                     "Maximum number of masked LM predictions per sequence.")
+
+flags.DEFINE_integer("random_seed", 12345, "Random seed for data generation.")
+
+flags.DEFINE_integer(
+    "dupe_factor", 10,
+    "Number of times to duplicate the input data (with different masks).")
+
+flags.DEFINE_float("masked_lm_prob", 0.15, "Masked LM probability.")
+
+flags.DEFINE_float(
+    "short_seq_prob", 0.1,
+    "Probability of creating sequences which are shorter than the "
+    "maximum length.")
+
+
+class TrainingInstance(object):
+  """A single training instance (sentence pair)."""
+
+  def __init__(self, tokens, segment_ids, masked_lm_positions, masked_lm_labels,
+               is_random_next):
+    self.tokens = tokens
+    self.segment_ids = segment_ids
+    self.is_random_next = is_random_next
+    self.masked_lm_positions = masked_lm_positions
+    self.masked_lm_labels = masked_lm_labels
+
+  def __str__(self):
+    s = ""
+    s += "tokens: %s\n" % (" ".join(
+        [tokenization.printable_text(x) for x in self.tokens]))
+    s += "segment_ids: %s\n" % (" ".join([str(x) for x in self.segment_ids]))
+    s += "is_random_next: %s\n" % self.is_random_next
+    s += "masked_lm_positions: %s\n" % (" ".join(
+        [str(x) for x in self.masked_lm_positions]))
+    s += "masked_lm_labels: %s\n" % (" ".join(
+        [tokenization.printable_text(x) for x in self.masked_lm_labels]))
+    s += "\n"
+    return s
+
+  def __repr__(self):
+    return self.__str__()
+
+
+def write_instance_to_example_files(instances, tokenizer, max_seq_length,
+                                    max_predictions_per_seq, output_files):
+  """Create TF example files from `TrainingInstance`s."""
+  writers = []
+  for output_file in output_files:
+    writers.append(tf.python_io.TFRecordWriter(output_file))
+
+  writer_index = 0
+
+  total_written = 0
+  for (inst_index, instance) in enumerate(instances):
+    input_ids = tokenizer.convert_tokens_to_ids(instance.tokens)
+    input_mask = [1] * len(input_ids)
+    segment_ids = list(instance.segment_ids)
+    assert len(input_ids) <= max_seq_length
+
+    while len(input_ids) < max_seq_length:
+      input_ids.append(0)
+      input_mask.append(0)
+      segment_ids.append(0)
+
+    assert len(input_ids) == max_seq_length
+    assert len(input_mask) == max_seq_length
+    assert len(segment_ids) == max_seq_length
+
+    masked_lm_positions = list(instance.masked_lm_positions)
+    masked_lm_ids = tokenizer.convert_tokens_to_ids(instance.masked_lm_labels)
+    masked_lm_weights = [1.0] * len(masked_lm_ids)
+
+    while len(masked_lm_positions) < max_predictions_per_seq:
+      masked_lm_positions.append(0)
+      masked_lm_ids.append(0)
+      masked_lm_weights.append(0.0)
+
+    next_sentence_label = 1 if instance.is_random_next else 0
+
+    features = collections.OrderedDict()
+    features["input_ids"] = create_int_feature(input_ids)
+    features["input_mask"] = create_int_feature(input_mask)
+    features["segment_ids"] = create_int_feature(segment_ids)
+    features["masked_lm_positions"] = create_int_feature(masked_lm_positions)
+    features["masked_lm_ids"] = create_int_feature(masked_lm_ids)
+    features["masked_lm_weights"] = create_float_feature(masked_lm_weights)
+    features["next_sentence_labels"] = create_int_feature([next_sentence_label])
+
+    tf_example = tf.train.Example(features=tf.train.Features(feature=features))
+
+    writers[writer_index].write(tf_example.SerializeToString())
+    writer_index = (writer_index + 1) % len(writers)
+
+    total_written += 1
+
+    if inst_index < 20:
+      tf.logging.info("*** Example ***")
+      tf.logging.info("tokens: %s" % " ".join(
+          [tokenization.printable_text(x) for x in instance.tokens]))
+
+      for feature_name in features.keys():
+        feature = features[feature_name]
+        values = []
+        if feature.int64_list.value:
+          values = feature.int64_list.value
+        elif feature.float_list.value:
+          values = feature.float_list.value
+        tf.logging.info(
+            "%s: %s" % (feature_name, " ".join([str(x) for x in values])))
+
+  for writer in writers:
+    writer.close()
+
+  tf.logging.info("Wrote %d total instances", total_written)
+
+
+def create_int_feature(values):
+  feature = tf.train.Feature(int64_list=tf.train.Int64List(value=list(values)))
+  return feature
+
+
+def create_float_feature(values):
+  feature = tf.train.Feature(float_list=tf.train.FloatList(value=list(values)))
+  return feature
+
+
+def create_training_instances(input_files, tokenizer, max_seq_length,
+                              dupe_factor, short_seq_prob, masked_lm_prob,
+                              max_predictions_per_seq, rng):
+  """Create `TrainingInstance`s from raw text."""
+  all_documents = [[]]
+
+  # Input file format:
+  # (1) One sentence per line. These should ideally be actual sentences, not
+  # entire paragraphs or arbitrary spans of text. (Because we use the
+  # sentence boundaries for the "next sentence prediction" task).
+  # (2) Blank lines between documents. Document boundaries are needed so
+  # that the "next sentence prediction" task doesn't span between documents.
+  for input_file in input_files:
+    with tf.gfile.GFile(input_file, "r") as reader:
+      while True:
+        line = tokenization.convert_to_unicode(reader.readline())
+        if not line:
+          break
+        line = line.strip()
+
+        # Empty lines are used as document delimiters
+        if not line:
+          all_documents.append([])
+        tokens = tokenizer.tokenize(line)
+        if tokens:
+          all_documents[-1].append(tokens)
+
+  # Remove empty documents
+  all_documents = [x for x in all_documents if x]
+  rng.shuffle(all_documents)
+
+  vocab_words = list(tokenizer.vocab.keys())
+  instances = []
+  for _ in range(dupe_factor):
+    for document_index in range(len(all_documents)):
+      instances.extend(
+          create_instances_from_document(
+              all_documents, document_index, max_seq_length, short_seq_prob,
+              masked_lm_prob, max_predictions_per_seq, vocab_words, rng))
+
+  rng.shuffle(instances)
+  return instances
+
+
+def create_instances_from_document(
+    all_documents, document_index, max_seq_length, short_seq_prob,
+    masked_lm_prob, max_predictions_per_seq, vocab_words, rng):
+  """Creates `TrainingInstance`s for a single document."""
+  document = all_documents[document_index]
+
+  # Account for [CLS], [SEP], [SEP]
+  max_num_tokens = max_seq_length - 3
+
+  # We *usually* want to fill up the entire sequence since we are padding
+  # to `max_seq_length` anyways, so short sequences are generally wasted
+  # computation. However, we *sometimes*
+  # (i.e., short_seq_prob == 0.1 == 10% of the time) want to use shorter
+  # sequences to minimize the mismatch between pre-training and fine-tuning.
+  # The `target_seq_length` is just a rough target however, whereas
+  # `max_seq_length` is a hard limit.
+  target_seq_length = max_num_tokens
+  if rng.random() < short_seq_prob:
+    target_seq_length = rng.randint(2, max_num_tokens)
+
+  # We DON'T just concatenate all of the tokens from a document into a long
+  # sequence and choose an arbitrary split point because this would make the
+  # next sentence prediction task too easy. Instead, we split the input into
+  # segments "A" and "B" based on the actual "sentences" provided by the user
+  # input.
+  instances = []
+  current_chunk = []
+  current_length = 0
+  i = 0
+  while i < len(document):
+    segment = document[i]
+    current_chunk.append(segment)
+    current_length += len(segment)
+    if i == len(document) - 1 or current_length >= target_seq_length:
+      if current_chunk:
+        # `a_end` is how many segments from `current_chunk` go into the `A`
+        # (first) sentence.
+        a_end = 1
+        if len(current_chunk) >= 2:
+          a_end = rng.randint(1, len(current_chunk) - 1)
+
+        tokens_a = []
+        for j in range(a_end):
+          tokens_a.extend(current_chunk[j])
+
+        tokens_b = []
+        # Random next
+        is_random_next = False
+        if len(current_chunk) == 1 or rng.random() < 0.5:
+          is_random_next = True
+          target_b_length = target_seq_length - len(tokens_a)
+
+          # This should rarely go for more than one iteration for large
+          # corpora. However, just to be careful, we try to make sure that
+          # the random document is not the same as the document
+          # we're processing.
+          for _ in range(10):
+            random_document_index = rng.randint(0, len(all_documents) - 1)
+            if random_document_index != document_index:
+              break
+
+          random_document = all_documents[random_document_index]
+          random_start = rng.randint(0, len(random_document) - 1)
+          for j in range(random_start, len(random_document)):
+            tokens_b.extend(random_document[j])
+            if len(tokens_b) >= target_b_length:
+              break
+          # We didn't actually use these segments so we "put them back" so
+          # they don't go to waste.
+          num_unused_segments = len(current_chunk) - a_end
+          i -= num_unused_segments
+        # Actual next
+        else:
+          is_random_next = False
+          for j in range(a_end, len(current_chunk)):
+            tokens_b.extend(current_chunk[j])
+        truncate_seq_pair(tokens_a, tokens_b, max_num_tokens, rng)
+
+        assert len(tokens_a) >= 1
+        assert len(tokens_b) >= 1
+
+        tokens = []
+        segment_ids = []
+        tokens.append("[CLS]")
+        segment_ids.append(0)
+        for token in tokens_a:
+          tokens.append(token)
+          segment_ids.append(0)
+
+        tokens.append("[SEP]")
+        segment_ids.append(0)
+
+        for token in tokens_b:
+          tokens.append(token)
+          segment_ids.append(1)
+        tokens.append("[SEP]")
+        segment_ids.append(1)
+
+        (tokens, masked_lm_positions,
+         masked_lm_labels) = create_masked_lm_predictions(
+             tokens, masked_lm_prob, max_predictions_per_seq, vocab_words, rng)
+        instance = TrainingInstance(
+            tokens=tokens,
+            segment_ids=segment_ids,
+            is_random_next=is_random_next,
+            masked_lm_positions=masked_lm_positions,
+            masked_lm_labels=masked_lm_labels)
+        instances.append(instance)
+      current_chunk = []
+      current_length = 0
+    i += 1
+
+  return instances
+
+
+def create_masked_lm_predictions(tokens, masked_lm_prob,
+                                 max_predictions_per_seq, vocab_words, rng):
+  """Creates the predictis for the masked LM objective."""
+
+  cand_indexes = []
+  for (i, token) in enumerate(tokens):
+    if token == "[CLS]" or token == "[SEP]":
+      continue
+    cand_indexes.append(i)
+
+  rng.shuffle(cand_indexes)
+
+  output_tokens = list(tokens)
+
+  masked_lm = collections.namedtuple("masked_lm", ["index", "label"])  # pylint: disable=invalid-name
+
+  num_to_predict = min(max_predictions_per_seq,
+                       max(1, int(round(len(tokens) * masked_lm_prob))))
+
+  masked_lms = []
+  covered_indexes = set()
+  for index in cand_indexes:
+    if len(masked_lms) >= num_to_predict:
+      break
+    if index in covered_indexes:
+      continue
+    covered_indexes.add(index)
+
+    masked_token = None
+    # 80% of the time, replace with [MASK]
+    if rng.random() < 0.8:
+      masked_token = "[MASK]"
+    else:
+      # 10% of the time, keep original
+      if rng.random() < 0.5:
+        masked_token = tokens[index]
+      # 10% of the time, replace with random word
+      else:
+        masked_token = vocab_words[rng.randint(0, len(vocab_words) - 1)]
+
+    output_tokens[index] = masked_token
+
+    masked_lms.append(masked_lm(index=index, label=tokens[index]))
+
+  masked_lms = sorted(masked_lms, key=lambda x: x.index)
+
+  masked_lm_positions = []
+  masked_lm_labels = []
+  for p in masked_lms:
+    masked_lm_positions.append(p.index)
+    masked_lm_labels.append(p.label)
+
+  return (output_tokens, masked_lm_positions, masked_lm_labels)
+
+
+def truncate_seq_pair(tokens_a, tokens_b, max_num_tokens, rng):
+  """Truncates a pair of sequences to a maximum sequence length."""
+  while True:
+    total_length = len(tokens_a) + len(tokens_b)
+    if total_length <= max_num_tokens:
+      break
+
+    trunc_tokens = tokens_a if len(tokens_a) > len(tokens_b) else tokens_b
+    assert len(trunc_tokens) >= 1
+
+    # We want to sometimes truncate from the front and sometimes from the
+    # back to add more randomness and avoid biases.
+    if rng.random() < 0.5:
+      del trunc_tokens[0]
+    else:
+      trunc_tokens.pop()
+
+
+def main(_):
+  tf.logging.set_verbosity(tf.logging.INFO)
+
+  tokenizer = tokenization.FullTokenizer(
+      vocab_file=FLAGS.vocab_file, do_lower_case=FLAGS.do_lower_case)
+
+  input_files = []
+  for input_pattern in FLAGS.input_file.split(","):
+    input_files.extend(tf.gfile.Glob(input_pattern))
+
+  tf.logging.info("*** Reading from input files ***")
+  for input_file in input_files:
+    tf.logging.info("  %s", input_file)
+
+  rng = random.Random(FLAGS.random_seed)
+  instances = create_training_instances(
+      input_files, tokenizer, FLAGS.max_seq_length, FLAGS.dupe_factor,
+      FLAGS.short_seq_prob, FLAGS.masked_lm_prob, FLAGS.max_predictions_per_seq,
+      rng)
+
+  output_files = FLAGS.output_file.split(",")
+  tf.logging.info("*** Writing to output files ***")
+  for output_file in output_files:
+    tf.logging.info("  %s", output_file)
+
+  write_instance_to_example_files(instances, tokenizer, FLAGS.max_seq_length,
+                                  FLAGS.max_predictions_per_seq, output_files)
+
+
+if __name__ == "__main__":
+  flags.mark_flag_as_required("input_file")
+  flags.mark_flag_as_required("output_file")
+  flags.mark_flag_as_required("vocab_file")
+  tf.app.run()

download_weights.sh

-echo "=== Downloading BERT pre-trained weights ==="
-echo "---"
-wget --quiet --continue http://www.fit.vutbr.cz/~imikolov/rnnlm/simple-examples.tgz
-tar -xzf simple-examples.tgz
-rm -rf simple-examples.tgz

extract_features.py

+# coding=utf-8
+# Copyright 2018 The Google AI Language Team Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Extract pre-computed feature vectors from BERT."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import codecs
+import collections
+import json
+import re
+
+import modeling
+import tokenization
+import tensorflow as tf
+
+flags = tf.flags
+
+FLAGS = flags.FLAGS
+
+flags.DEFINE_string("input_file", None, "")
+
+flags.DEFINE_string("output_file", None, "")
+
+flags.DEFINE_string("layers", "-1,-2,-3,-4", "")
+
+flags.DEFINE_string(
+    "bert_config_file", None,
+    "The config json file corresponding to the pre-trained BERT model. "
+    "This specifies the model architecture.")
+
+flags.DEFINE_integer(
+    "max_seq_length", 128,
+    "The maximum total input sequence length after WordPiece tokenization. "
+    "Sequences longer than this will be truncated, and sequences shorter "
+    "than this will be padded.")
+
+flags.DEFINE_string(
+    "init_checkpoint", None,
+    "Initial checkpoint (usually from a pre-trained BERT model).")
+
+flags.DEFINE_string("vocab_file", None,
+                    "The vocabulary file that the BERT model was trained on.")
+
+flags.DEFINE_bool(
+    "do_lower_case", True,
+    "Whethre to lower case the input text. Should be True for uncased "
+    "models and False for cased models.")
+
+flags.DEFINE_integer("batch_size", 32, "Batch size for predictions.")
+
+flags.DEFINE_bool("use_tpu", False, "Whether to use TPU or GPU/CPU.")
+
+flags.DEFINE_string("master", None,
+                    "If using a TPU, the address of the master.")
+
+flags.DEFINE_integer(
+    "num_tpu_cores", 8,
+    "Only used if `use_tpu` is True. Total number of TPU cores to use.")
+
+flags.DEFINE_bool(
+    "use_one_hot_embeddings", False,
+    "If True, tf.one_hot will be used for embedding lookups, otherwise "
+    "tf.nn.embedding_lookup will be used. On TPUs, this should be True "
+    "since it is much faster.")
+
+
+class InputExample(object):
+
+  def __init__(self, unique_id, text_a, text_b):
+    self.unique_id = unique_id
+    self.text_a = text_a
+    self.text_b = text_b
+
+
+class InputFeatures(object):
+  """A single set of features of data."""
+
+  def __init__(self, unique_id, tokens, input_ids, input_mask, input_type_ids):
+    self.unique_id = unique_id
+    self.tokens = tokens
+    self.input_ids = input_ids
+    self.input_mask = input_mask
+    self.input_type_ids = input_type_ids
+
+
+def input_fn_builder(features, seq_length):
+  """Creates an `input_fn` closure to be passed to TPUEstimator."""
+
+  all_unique_ids = []
+  all_input_ids = []
+  all_input_mask = []
+  all_input_type_ids = []
+
+  for feature in features:
+    all_unique_ids.append(feature.unique_id)
+    all_input_ids.append(feature.input_ids)
+    all_input_mask.append(feature.input_mask)
+    all_input_type_ids.append(feature.input_type_ids)
+
+  def input_fn(params):
+    """The actual input function."""
+    batch_size = params["batch_size"]
+
+    num_examples = len(features)
+
+    # This is for demo purposes and does NOT scale to large data sets. We do
+    # not use Dataset.from_generator() because that uses tf.py_func which is
+    # not TPU compatible. The right way to load data is with TFRecordReader.
+    d = tf.data.Dataset.from_tensor_slices({
+        "unique_ids":
+            tf.constant(all_unique_ids, shape=[num_examples], dtype=tf.int32),
+        "input_ids":
+            tf.constant(
+                all_input_ids, shape=[num_examples, seq_length],
+                dtype=tf.int32),
+        "input_mask":
+            tf.constant(
+                all_input_mask,
+                shape=[num_examples, seq_length],
+                dtype=tf.int32),
+        "input_type_ids":
+            tf.constant(
+                all_input_type_ids,
+                shape=[num_examples, seq_length],
+                dtype=tf.int32),
+    })
+
+    d = d.batch(batch_size=batch_size, drop_remainder=False)
+    return d
+
+  return input_fn
+
+
+def model_fn_builder(bert_config, init_checkpoint, layer_indexes, use_tpu,
+                     use_one_hot_embeddings):
+  """Returns `model_fn` closure for TPUEstimator."""
+
+  def model_fn(features, labels, mode, params):  # pylint: disable=unused-argument
+    """The `model_fn` for TPUEstimator."""
+
+    unique_ids = features["unique_ids"]
+    input_ids = features["input_ids"]
+    input_mask = features["input_mask"]
+    input_type_ids = features["input_type_ids"]
+
+    model = modeling.BertModel(
+        config=bert_config,
+        is_training=False,
+        input_ids=input_ids,
+        input_mask=input_mask,
+        token_type_ids=input_type_ids,
+        use_one_hot_embeddings=use_one_hot_embeddings)
+
+    if mode != tf.estimator.ModeKeys.PREDICT:
+      raise ValueError("Only PREDICT modes are supported: %s" % (mode))
+
+    tvars = tf.trainable_variables()
+    scaffold_fn = None
+    (assignment_map, _) = modeling.get_assigment_map_from_checkpoint(
+        tvars, init_checkpoint)
+    if use_tpu:
+
+      def tpu_scaffold():
+        tf.train.init_from_checkpoint(init_checkpoint, assignment_map)
+        return tf.train.Scaffold()
+
+      scaffold_fn = tpu_scaffold
+    else:
+      tf.train.init_from_checkpoint(init_checkpoint, assignment_map)
+
+    all_layers = model.get_all_encoder_layers()
+
+    predictions = {
+        "unique_id": unique_ids,
+    }
+
+    for (i, layer_index) in enumerate(layer_indexes):
+      predictions["layer_output_%d" % i] = all_layers[layer_index]
+
+    output_spec = tf.contrib.tpu.TPUEstimatorSpec(
+        mode=mode, predictions=predictions, scaffold_fn=scaffold_fn)
+    return output_spec
+
+  return model_fn
+
+
+def convert_examples_to_features(examples, seq_length, tokenizer):
+  """Loads a data file into a list of `InputBatch`s."""
+
+  features = []
+  for (ex_index, example) in enumerate(examples):
+    tokens_a = tokenizer.tokenize(example.text_a)
+
+    tokens_b = None
+    if example.text_b:
+      tokens_b = tokenizer.tokenize(example.text_b)
+
+    if tokens_b:
+      # Modifies `tokens_a` and `tokens_b` in place so that the total
+      # length is less than the specified length.
+      # Account for [CLS], [SEP], [SEP] with "- 3"
+      _truncate_seq_pair(tokens_a, tokens_b, seq_length - 3)
+    else:
+      # Account for [CLS] and [SEP] with "- 2"
+      if len(tokens_a) > seq_length - 2:
+        tokens_a = tokens_a[0:(seq_length - 2)]
+
+    # The convention in BERT is:
+    # (a) For sequence pairs:
+    #  tokens:   [CLS] is this jack ##son ##ville ? [SEP] no it is not . [SEP]
+    #  type_ids: 0   0  0    0    0     0       0 0    1  1  1  1   1 1
+    # (b) For single sequences:
+    #  tokens:   [CLS] the dog is hairy . [SEP]
+    #  type_ids: 0   0   0   0  0     0 0
+    #
+    # Where "type_ids" are used to indicate whether this is the first
+    # sequence or the second sequence. The embedding vectors for `type=0` and
+    # `type=1` were learned during pre-training and are added to the wordpiece
+    # embedding vector (and position vector). This is not *strictly* necessary
+    # since the [SEP] token unambigiously separates the sequences, but it makes
+    # it easier for the model to learn the concept of sequences.
+    #
+    # For classification tasks, the first vector (corresponding to [CLS]) is
+    # used as as the "sentence vector". Note that this only makes sense because
+    # the entire model is fine-tuned.
+    tokens = []
+    input_type_ids = []
+    tokens.append("[CLS]")
+    input_type_ids.append(0)
+    for token in tokens_a:
+      tokens.append(token)
+      input_type_ids.append(0)
+    tokens.append("[SEP]")
+    input_type_ids.append(0)
+
+    if tokens_b:
+      for token in tokens_b:
+        tokens.append(token)
+        input_type_ids.append(1)
+      tokens.append("[SEP]")
+      input_type_ids.append(1)
+
+    input_ids = tokenizer.convert_tokens_to_ids(tokens)
+
+    # The mask has 1 for real tokens and 0 for padding tokens. Only real
+    # tokens are attended to.
+    input_mask = [1] * len(input_ids)
+
+    # Zero-pad up to the sequence length.
+    while len(input_ids) < seq_length:
+      input_ids.append(0)
+      input_mask.append(0)
+      input_type_ids.append(0)
+
+    assert len(input_ids) == seq_length
+    assert len(input_mask) == seq_length
+    assert len(input_type_ids) == seq_length
+
+    if ex_index < 5:
+      tf.logging.info("*** Example ***")
+      tf.logging.info("unique_id: %s" % (example.unique_id))
+      tf.logging.info("tokens: %s" % " ".join([str(x) for x in tokens]))
+      tf.logging.info("input_ids: %s" % " ".join([str(x) for x in input_ids]))
+      tf.logging.info("input_mask: %s" % " ".join([str(x) for x in input_mask]))
+      tf.logging.info(
+          "input_type_ids: %s" % " ".join([str(x) for x in input_type_ids]))
+
+    features.append(
+        InputFeatures(
+            unique_id=example.unique_id,
+            tokens=tokens,
+            input_ids=input_ids,
+            input_mask=input_mask,
+            input_type_ids=input_type_ids))
+  return features
+
+
+def _truncate_seq_pair(tokens_a, tokens_b, max_length):
+  """Truncates a sequence pair in place to the maximum length."""
+
+  # This is a simple heuristic which will always truncate the longer sequence
+  # one token at a time. This makes more sense than truncating an equal percent
+  # of tokens from each, since if one sequence is very short then each token
+  # that's truncated likely contains more information than a longer sequence.
+  while True:
+    total_length = len(tokens_a) + len(tokens_b)
+    if total_length <= max_length:
+      break
+    if len(tokens_a) > len(tokens_b):
+      tokens_a.pop()
+    else:
+      tokens_b.pop()
+
+
+def read_examples(input_file):
+  """Read a list of `InputExample`s from an input file."""
+  examples = []
+  unique_id = 0
+  with tf.gfile.GFile(input_file, "r") as reader:
+    while True:
+      line = tokenization.convert_to_unicode(reader.readline())
+      if not line:
+        break
+      line = line.strip()
+      text_a = None
+      text_b = None
+      m = re.match(r"^(.*) \|\|\| (.*)$", line)
+      if m is None:
+        text_a = line
+      else:
+        text_a = m.group(1)
+        text_b = m.group(2)
+      examples.append(
+          InputExample(unique_id=unique_id, text_a=text_a, text_b=text_b))
+      unique_id += 1
+  return examples
+
+
+def main(_):
+  tf.logging.set_verbosity(tf.logging.INFO)
+
+  layer_indexes = [int(x) for x in FLAGS.layers.split(",")]
+
+  bert_config = modeling.BertConfig.from_json_file(FLAGS.bert_config_file)
+
+  tokenizer = tokenization.FullTokenizer(
+      vocab_file=FLAGS.vocab_file, do_lower_case=FLAGS.do_lower_case)
+
+  is_per_host = tf.contrib.tpu.InputPipelineConfig.PER_HOST_V2
+  run_config = tf.contrib.tpu.RunConfig(
+      master=FLAGS.master,
+      tpu_config=tf.contrib.tpu.TPUConfig(
+          num_shards=FLAGS.num_tpu_cores,
+          per_host_input_for_training=is_per_host))
+
+  examples = read_examples(FLAGS.input_file)
+
+  features = convert_examples_to_features(
+      examples=examples, seq_length=FLAGS.max_seq_length, tokenizer=tokenizer)
+
+  unique_id_to_feature = {}
+  for feature in features:
+    unique_id_to_feature[feature.unique_id] = feature
+
+  model_fn = model_fn_builder(
+      bert_config=bert_config,
+      init_checkpoint=FLAGS.init_checkpoint,
+      layer_indexes=layer_indexes,
+      use_tpu=FLAGS.use_tpu,
+      use_one_hot_embeddings=FLAGS.use_one_hot_embeddings)
+
+  # If TPU is not available, this will fall back to normal Estimator on CPU
+  # or GPU.
+  estimator = tf.contrib.tpu.TPUEstimator(
+      use_tpu=FLAGS.use_tpu,
+      model_fn=model_fn,
+      config=run_config,
+      predict_batch_size=FLAGS.batch_size)
+
+  input_fn = input_fn_builder(
+      features=features, seq_length=FLAGS.max_seq_length)
+
+  with codecs.getwriter("utf-8")(tf.gfile.Open(FLAGS.output_file,
+                                               "w")) as writer:
+    for result in estimator.predict(input_fn, yield_single_examples=True):
+      unique_id = int(result["unique_id"])
+      feature = unique_id_to_feature[unique_id]
+      output_json = collections.OrderedDict()
+      output_json["linex_index"] = unique_id
+      all_features = []
+      for (i, token) in enumerate(feature.tokens):
+        all_layers = []
+        for (j, layer_index) in enumerate(layer_indexes):
+          layer_output = result["layer_output_%d" % j]
+          layers = collections.OrderedDict()
+          layers["index"] = layer_index
+          layers["values"] = [
+              round(float(x), 6) for x in layer_output[i:(i + 1)].flat
+          ]
+          all_layers.append(layers)
+        features = collections.OrderedDict()
+        features["token"] = token
+        features["layers"] = all_layers
+        all_features.append(features)
+      output_json["features"] = all_features
+      writer.write(json.dumps(output_json) + "\n")
+
+
+if __name__ == "__main__":
+  flags.mark_flag_as_required("input_file")
+  flags.mark_flag_as_required("vocab_file")
+  flags.mark_flag_as_required("bert_config_file")
+  flags.mark_flag_as_required("init_checkpoint")
+  flags.mark_flag_as_required("output_file")
+  tf.app.run()

modeling_test.py

+# coding=utf-8
+# Copyright 2018 The Google AI Language Team Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import collections
+import json
+import random
+import re
+
+import modeling
+import six
+import tensorflow as tf
+
+
+class BertModelTest(tf.test.TestCase):
+
+  class BertModelTester(object):
+
+    def __init__(self,
+                 parent,
+                 batch_size=13,
+                 seq_length=7,
+                 is_training=True,
+                 use_input_mask=True,
+                 use_token_type_ids=True,
+                 vocab_size=99,
+                 hidden_size=32,
+                 num_hidden_layers=5,
+                 num_attention_heads=4,
+                 intermediate_size=37,
+                 hidden_act="gelu",
+                 hidden_dropout_prob=0.1,
+                 attention_probs_dropout_prob=0.1,
+                 max_position_embeddings=512,
+                 type_vocab_size=16,
+                 initializer_range=0.02,
+                 scope=None):
+      self.parent = parent
+      self.batch_size = batch_size
+      self.seq_length = seq_length
+      self.is_training = is_training
+      self.use_input_mask = use_input_mask
+      self.use_token_type_ids = use_token_type_ids
+      self.vocab_size = vocab_size
+      self.hidden_size = hidden_size
+      self.num_hidden_layers = num_hidden_layers
+      self.num_attention_heads = num_attention_heads
+      self.intermediate_size = intermediate_size
+      self.hidden_act = hidden_act
+      self.hidden_dropout_prob = hidden_dropout_prob
+      self.attention_probs_dropout_prob = attention_probs_dropout_prob
+      self.max_position_embeddings = max_position_embeddings
+      self.type_vocab_size = type_vocab_size
+      self.initializer_range = initializer_range
+      self.scope = scope
+
+    def create_model(self):
+      input_ids = BertModelTest.ids_tensor([self.batch_size, self.seq_length],
+                                           self.vocab_size)
+
+      input_mask = None
+      if self.use_input_mask:
+        input_mask = BertModelTest.ids_tensor(
+            [self.batch_size, self.seq_length], vocab_size=2)
+
+      token_type_ids = None
+      if self.use_token_type_ids:
+        token_type_ids = BertModelTest.ids_tensor(
+            [self.batch_size, self.seq_length], self.type_vocab_size)
+
+      config = modeling.BertConfig(
+          vocab_size=self.vocab_size,
+          hidden_size=self.hidden_size,
+          num_hidden_layers=self.num_hidden_layers,
+          num_attention_heads=self.num_attention_heads,
+          intermediate_size=self.intermediate_size,
+          hidden_act=self.hidden_act,
+          hidden_dropout_prob=self.hidden_dropout_prob,
+          attention_probs_dropout_prob=self.attention_probs_dropout_prob,
+          max_position_embeddings=self.max_position_embeddings,
+          type_vocab_size=self.type_vocab_size,
+          initializer_range=self.initializer_range)
+
+      model = modeling.BertModel(
+          config=config,
+          is_training=self.is_training,
+          input_ids=input_ids,
+          input_mask=input_mask,
+          token_type_ids=token_type_ids,
+          scope=self.scope)
+
+      outputs = {
+          "embedding_output": model.get_embedding_output(),
+          "sequence_output": model.get_sequence_output(),
+          "pooled_output": model.get_pooled_output(),
+          "all_encoder_layers": model.get_all_encoder_layers(),
+      }
+      return outputs
+
+    def check_output(self, result):
+      self.parent.assertAllEqual(
+          result["embedding_output"].shape,
+          [self.batch_size, self.seq_length, self.hidden_size])
+
+      self.parent.assertAllEqual(
+          result["sequence_output"].shape,
+          [self.batch_size, self.seq_length, self.hidden_size])
+
+      self.parent.assertAllEqual(result["pooled_output"].shape,
+                                 [self.batch_size, self.hidden_size])
+
+  def test_default(self):
+    self.run_tester(BertModelTest.BertModelTester(self))
+
+  def test_config_to_json_string(self):
+    config = modeling.BertConfig(vocab_size=99, hidden_size=37)
+    obj = json.loads(config.to_json_string())
+    self.assertEqual(obj["vocab_size"], 99)
+    self.assertEqual(obj["hidden_size"], 37)
+
+  def run_tester(self, tester):
+    with self.test_session() as sess:
+      ops = tester.create_model()
+      init_op = tf.group(tf.global_variables_initializer(),
+                         tf.local_variables_initializer())
+      sess.run(init_op)
+      output_result = sess.run(ops)
+      tester.check_output(output_result)
+
+      self.assert_all_tensors_reachable(sess, [init_op, ops])
+
+  @classmethod
+  def ids_tensor(cls, shape, vocab_size, rng=None, name=None):
+    """Creates a random int32 tensor of the shape within the vocab size."""
+    if rng is None:
+      rng = random.Random()
+
+    total_dims = 1
+    for dim in shape:
+      total_dims *= dim
+
+    values = []
+    for _ in range(total_dims):
+      values.append(rng.randint(0, vocab_size - 1))
+
+    return tf.constant(value=values, dtype=tf.int32, shape=shape, name=name)
+
+  def assert_all_tensors_reachable(self, sess, outputs):
+    """Checks that all the tensors in the graph are reachable from outputs."""
+    graph = sess.graph
+
+    ignore_strings = [
+        "^.*/dilation_rate$",
+        "^.*/Tensordot/concat$",
+        "^.*/Tensordot/concat/axis$",
+        "^testing/.*$",
+    ]
+
+    ignore_regexes = [re.compile(x) for x in ignore_strings]
+
+    unreachable = self.get_unreachable_ops(graph, outputs)
+    filtered_unreachable = []
+    for x in unreachable:
+      do_ignore = False
+      for r in ignore_regexes:
+        m = r.match(x.name)
+        if m is not None:
+          do_ignore = True
+      if do_ignore:
+        continue
+      filtered_unreachable.append(x)
+    unreachable = filtered_unreachable
+
+    self.assertEqual(
+        len(unreachable), 0, "The following ops are unreachable: %s" %
+        (" ".join([x.name for x in unreachable])))
+
+  @classmethod
+  def get_unreachable_ops(cls, graph, outputs):
+    """Finds all of the tensors in graph that are unreachable from outputs."""
+    outputs = cls.flatten_recursive(outputs)
+    output_to_op = collections.defaultdict(list)
+    op_to_all = collections.defaultdict(list)
+    assign_out_to_in = collections.defaultdict(list)
+
+    for op in graph.get_operations():
+      for x in op.inputs:
+        op_to_all[op.name].append(x.name)
+      for y in op.outputs:
+        output_to_op[y.name].append(op.name)
+        op_to_all[op.name].append(y.name)
+      if str(op.type) == "Assign":
+        for y in op.outputs:
+          for x in op.inputs:
+            assign_out_to_in[y.name].append(x.name)
+
+    assign_groups = collections.defaultdict(list)
+    for out_name in assign_out_to_in.keys():
+      name_group = assign_out_to_in[out_name]
+      for n1 in name_group:
+        assign_groups[n1].append(out_name)
+        for n2 in name_group:
+          if n1 != n2:
+            assign_groups[n1].append(n2)
+
+    seen_tensors = {}
+    stack = [x.name for x in outputs]
+    while stack:
+      name = stack.pop()
+      if name in seen_tensors:
+        continue
+      seen_tensors[name] = True
+
+      if name in output_to_op:
+        for op_name in output_to_op[name]:
+          if op_name in op_to_all:
+            for input_name in op_to_all[op_name]:
+              if input_name not in stack:
+                stack.append(input_name)
+
+      expanded_names = []
+      if name in assign_groups:
+        for assign_name in assign_groups[name]:
+          expanded_names.append(assign_name)
+
+      for expanded_name in expanded_names:
+        if expanded_name not in stack:
+          stack.append(expanded_name)
+
+    unreachable_ops = []
+    for op in graph.get_operations():
+      is_unreachable = False
+      all_names = [x.name for x in op.inputs] + [x.name for x in op.outputs]
+      for name in all_names:
+        if name not in seen_tensors:
+          is_unreachable = True
+      if is_unreachable:
+        unreachable_ops.append(op)
+    return unreachable_ops
+
+  @classmethod
+  def flatten_recursive(cls, item):
+    """Flattens (potentially nested) a tuple/dictionary/list to a list."""
+    output = []
+    if isinstance(item, list):
+      output.extend(item)
+    elif isinstance(item, tuple):
+      output.extend(list(item))
+    elif isinstance(item, dict):
+      for (_, v) in six.iteritems(item):
+        output.append(v)
+    else:
+      return [item]
+
+    flat_output = []
+    for x in output:
+      flat_output.extend(cls.flatten_recursive(x))
+    return flat_output
+
+
+if __name__ == "__main__":
+  tf.test.main()

optimization.py

+# coding=utf-8
+# Copyright 2018 The Google AI Language Team Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Functions and classes related to optimization (weight updates)."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import re
+import tensorflow as tf
+
+
+def create_optimizer(loss, init_lr, num_train_steps, num_warmup_steps, use_tpu):
+  """Creates an optimizer training op."""
+  global_step = tf.train.get_or_create_global_step()
+
+  learning_rate = tf.constant(value=init_lr, shape=[], dtype=tf.float32)
+
+  # Implements linear decay of the learning rate.
+  learning_rate = tf.train.polynomial_decay(
+      learning_rate,
+      global_step,
+      num_train_steps,
+      end_learning_rate=0.0,
+      power=1.0,
+      cycle=False)
+
+  # Implements linear warmup. I.e., if global_step < num_warmup_steps, the
+  # learning rate will be `global_step/num_warmup_steps * init_lr`.
+  if num_warmup_steps:
+    global_steps_int = tf.cast(global_step, tf.int32)
+    warmup_steps_int = tf.constant(num_warmup_steps, dtype=tf.int32)
+
+    global_steps_float = tf.cast(global_steps_int, tf.float32)
+    warmup_steps_float = tf.cast(warmup_steps_int, tf.float32)
+
+    warmup_percent_done = global_steps_float / warmup_steps_float
+    warmup_learning_rate = init_lr * warmup_percent_done
+
+    is_warmup = tf.cast(global_steps_int < warmup_steps_int, tf.float32)
+    learning_rate = (
+        (1.0 - is_warmup) * learning_rate + is_warmup * warmup_learning_rate)
+
+  # It is recommended that you use this optimizer for fine tuning, since this
+  # is how the model was trained (note that the Adam m/v variables are NOT
+  # loaded from init_checkpoint.)
+  optimizer = AdamWeightDecayOptimizer(
+      learning_rate=learning_rate,
+      weight_decay_rate=0.01,
+      beta_1=0.9,
+      beta_2=0.999,
+      epsilon=1e-6,
+      exclude_from_weight_decay=["LayerNorm", "layer_norm", "bias"])
+
+  if use_tpu:
+    optimizer = tf.contrib.tpu.CrossShardOptimizer(optimizer)
+
+  tvars = tf.trainable_variables()
+  grads = tf.gradients(loss, tvars)
+
+  # This is how the model was pre-trained.
+  (grads, _) = tf.clip_by_global_norm(grads, clip_norm=1.0)
+
+  train_op = optimizer.apply_gradients(
+      zip(grads, tvars), global_step=global_step)
+
+  new_global_step = global_step + 1
+  train_op = tf.group(train_op, [global_step.assign(new_global_step)])
+  return train_op
+
+
+class AdamWeightDecayOptimizer(tf.train.Optimizer):
+  """A basic Adam optimizer that includes "correct" L2 weight decay."""
+
+  def __init__(self,
+               learning_rate,
+               weight_decay_rate=0.0,
+               beta_1=0.9,
+               beta_2=0.999,
+               epsilon=1e-6,
+               exclude_from_weight_decay=None,
+               name="AdamWeightDecayOptimizer"):
+    """Constructs a AdamWeightDecayOptimizer."""
+    super(AdamWeightDecayOptimizer, self).__init__(False, name)
+
+    self.learning_rate = learning_rate
+    self.weight_decay_rate = weight_decay_rate
+    self.beta_1 = beta_1
+    self.beta_2 = beta_2
+    self.epsilon = epsilon
+    self.exclude_from_weight_decay = exclude_from_weight_decay
+
+  def apply_gradients(self, grads_and_vars, global_step=None, name=None):
+    """See base class."""
+    assignments = []
+    for (grad, param) in grads_and_vars:
+      if grad is None or param is None:
+        continue
+
+      param_name = self._get_variable_name(param.name)
+
+      m = tf.get_variable(
+          name=param_name + "/adam_m",
+          shape=param.shape.as_list(),
+          dtype=tf.float32,
+          trainable=False,
+          initializer=tf.zeros_initializer())
+      v = tf.get_variable(
+          name=param_name + "/adam_v",
+          shape=param.shape.as_list(),
+          dtype=tf.float32,
+          trainable=False,
+          initializer=tf.zeros_initializer())
+
+      # Standard Adam update.
+      next_m = (
+          tf.multiply(self.beta_1, m) + tf.multiply(1.0 - self.beta_1, grad))
+      next_v = (
+          tf.multiply(self.beta_2, v) + tf.multiply(1.0 - self.beta_2,
+                                                    tf.square(grad)))
+
+      update = next_m / (tf.sqrt(next_v) + self.epsilon)
+
+      # Just adding the square of the weights to the loss function is *not*
+      # the correct way of using L2 regularization/weight decay with Adam,
+      # since that will interact with the m and v parameters in strange ways.
+      #
+      # Instead we want ot decay the weights in a manner that doesn't interact
+      # with the m/v parameters. This is equivalent to adding the square
+      # of the weights to the loss with plain (non-momentum) SGD.
+      if self._do_use_weight_decay(param_name):
+        update += self.weight_decay_rate * param
+
+      update_with_lr = self.learning_rate * update
+
+      next_param = param - update_with_lr
+
+      assignments.extend(
+          [param.assign(next_param),
+           m.assign(next_m),
+           v.assign(next_v)])
+    return tf.group(*assignments, name=name)
+
+  def _do_use_weight_decay(self, param_name):
+    """Whether to use L2 weight decay for `param_name`."""
+    if not self.weight_decay_rate:
+      return False
+    if self.exclude_from_weight_decay:
+      for r in self.exclude_from_weight_decay:
+        if re.search(r, param_name) is not None:
+          return False
+    return True
+
+  def _get_variable_name(self, param_name):
+    """Get the variable name from the tensor name."""
+    m = re.match("^(.*):\\d+$", param_name)
+    if m is not None:
+      param_name = m.group(1)
+    return param_name

optimization_test.py

+# coding=utf-8
+# Copyright 2018 The Google AI Language Team Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import optimization
+import tensorflow as tf
+
+
+class OptimizationTest(tf.test.TestCase):
+
+  def test_adam(self):
+    with self.test_session() as sess:
+      w = tf.get_variable(
+          "w",
+          shape=[3],
+          initializer=tf.constant_initializer([0.1, -0.2, -0.1]))
+      x = tf.constant([0.4, 0.2, -0.5])
+      loss = tf.reduce_mean(tf.square(x - w))
+      tvars = tf.trainable_variables()
+      grads = tf.gradients(loss, tvars)
+      global_step = tf.train.get_or_create_global_step()
+      optimizer = optimization.AdamWeightDecayOptimizer(learning_rate=0.2)
+      train_op = optimizer.apply_gradients(zip(grads, tvars), global_step)
+      init_op = tf.group(tf.global_variables_initializer(),
+                         tf.local_variables_initializer())
+      sess.run(init_op)
+      for _ in range(100):
+        sess.run(train_op)
+      w_np = sess.run(w)
+      self.assertAllClose(w_np.flat, [0.4, 0.2, -0.5], rtol=1e-2, atol=1e-2)
+
+
+if __name__ == "__main__":
+  tf.test.main()

sample_text.txt

+This text is included to make sure Unicode is handled properly: 力加勝北区ᴵᴺᵀᵃছজটডণত
+Text should be one-sentence-per-line, with empty lines between documents.
+This sample text is public domain and was randomly selected from Project Guttenberg.
+
+The rain had only ceased with the gray streaks of morning at Blazing Star, and the settlement awoke to a moral sense of cleanliness, and the finding of forgotten knives, tin cups, and smaller camp utensils, where the heavy showers had washed away the debris and dust heaps before the cabin doors.
+Indeed, it was recorded in Blazing Star that a fortunate early riser had once picked up on the highway a solid chunk of gold quartz which the rain had freed from its incumbering soil, and washed into immediate and glittering popularity.
+Possibly this may have been the reason why early risers in that locality, during the rainy season, adopted a thoughtful habit of body, and seldom lifted their eyes to the rifted or india-ink washed skies above them.
+"Cass" Beard had risen early that morning, but not with a view to discovery.
+A leak in his cabin roof,--quite consistent with his careless, improvident habits,--had roused him at 4 A. M., with a flooded "bunk" and wet blankets.
+The chips from his wood pile refused to kindle a fire to dry his bed-clothes, and he had recourse to a more provident neighbor's to supply the deficiency.
+This was nearly opposite.
+Mr. Cassius crossed the highway, and stopped suddenly.
+Something glittered in the nearest red pool before him.
+Gold, surely!
+But, wonderful to relate, not an irregular, shapeless fragment of crude ore, fresh from Nature's crucible, but a bit of jeweler's handicraft in the form of a plain gold ring.
+Looking at it more attentively, he saw that it bore the inscription, "May to Cass."
+Like most of his fellow gold-seekers, Cass was superstitious.
+
+The fountain of classic wisdom, Hypatia herself.
+As the ancient sage--the name is unimportant to a monk--pumped water nightly that he might study by day, so I, the guardian of cloaks and parasols, at the sacred doors of her lecture-room, imbibe celestial knowledge.
+From my youth I felt in me a soul above the matter-entangled herd.
+She revealed to me the glorious fact, that I am a spark of Divinity itself.
+A fallen star, I am, sir!' continued he, pensively, stroking his lean stomach--'a fallen star!--fallen, if the dignity of philosophy will allow of the simile, among the hogs of the lower world--indeed, even into the hog-bucket itself. Well, after all, I will show you the way to the Archbishop's.
+There is a philosophic pleasure in opening one's treasures to the modest young.
+Perhaps you will assist me by carrying this basket of fruit?' And the little man jumped up, put his basket on Philammon's head, and trotted off up a neighbouring street.
+Philammon followed, half contemptuous, half wondering at what this philosophy might be, which could feed the self-conceit of anything so abject as his ragged little apish guide;
+but the novel roar and whirl of the street, the perpetual stream of busy faces, the line of curricles, palanquins, laden asses, camels, elephants, which met and passed him, and squeezed him up steps and into doorways, as they threaded their way through the great Moon-gate into the ample street beyond, drove everything from his mind but wondering curiosity, and a vague, helpless dread of that great living wilderness, more terrible than any dead wilderness of sand which he had left behind.
+Already he longed for the repose, the silence of the Laura--for faces which knew him and smiled upon him; but it was too late to turn back now.
+His guide held on for more than a mile up the great main street, crossed in the centre of the city, at right angles, by one equally magnificent, at each end of which, miles away, appeared, dim and distant over the heads of the living stream of passengers, the yellow sand-hills of the desert;
+while at the end of the vista in front of them gleamed the blue harbour, through a network of countless masts.
+At last they reached the quay at the opposite end of the street;
+and there burst on Philammon's astonished eyes a vast semicircle of blue sea, ringed with palaces and towers.
+He stopped involuntarily; and his little guide stopped also, and looked askance at the young monk, to watch the effect which that grand panorama should produce on him.

tokenization_test.py

+# coding=utf-8
+# Copyright 2018 The Google AI Language Team Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import os
+import tempfile
+
+import tokenization
+import tensorflow as tf
+
+
+class TokenizationTest(tf.test.TestCase):
+
+  def test_full_tokenizer(self):
+    vocab_tokens = [
+        "[UNK]", "[CLS]", "[SEP]", "want", "##want", "##ed", "wa", "un", "runn",
+        "##ing", ","
+    ]
+    with tempfile.NamedTemporaryFile(delete=False) as vocab_writer:
+      vocab_writer.write("".join([x + "\n" for x in vocab_tokens]))
+
+      vocab_file = vocab_writer.name
+
+    tokenizer = tokenization.FullTokenizer(vocab_file)
+    os.unlink(vocab_file)
+
+    tokens = tokenizer.tokenize(u"UNwant\u00E9d,running")
+    self.assertAllEqual(tokens, ["un", "##want", "##ed", ",", "runn", "##ing"])
+
+    self.assertAllEqual(
+        tokenizer.convert_tokens_to_ids(tokens), [7, 4, 5, 10, 8, 9])
+
+  def test_basic_tokenizer_lower(self):
+    tokenizer = tokenization.BasicTokenizer(do_lower_case=True)
+
+    self.assertAllEqual(
+        tokenizer.tokenize(u" \tHeLLo!how  \n Are yoU?  "),
+        ["hello", "!", "how", "are", "you", "?"])
+    self.assertAllEqual(tokenizer.tokenize(u"H\u00E9llo"), ["hello"])
+
+  def test_basic_tokenizer_no_lower(self):
+    tokenizer = tokenization.BasicTokenizer(do_lower_case=False)
+
+    self.assertAllEqual(
+        tokenizer.tokenize(u" \tHeLLo!how  \n Are yoU?  "),
+        ["HeLLo", "!", "how", "Are", "yoU", "?"])
+
+  def test_wordpiece_tokenizer(self):
+    vocab_tokens = [
+        "[UNK]", "[CLS]", "[SEP]", "want", "##want", "##ed", "wa", "un", "runn",
+        "##ing"
+    ]
+
+    vocab = {}
+    for (i, token) in enumerate(vocab_tokens):
+      vocab[token] = i
+    tokenizer = tokenization.WordpieceTokenizer(vocab=vocab)
+
+    self.assertAllEqual(tokenizer.tokenize(""), [])
+
+    self.assertAllEqual(
+        tokenizer.tokenize("unwanted running"),
+        ["un", "##want", "##ed", "runn", "##ing"])
+
+    self.assertAllEqual(
+        tokenizer.tokenize("unwantedX running"), ["[UNK]", "runn", "##ing"])
+
+  def test_convert_tokens_to_ids(self):
+    vocab_tokens = [
+        "[UNK]", "[CLS]", "[SEP]", "want", "##want", "##ed", "wa", "un", "runn",
+        "##ing"
+    ]
+
+    vocab = {}
+    for (i, token) in enumerate(vocab_tokens):
+      vocab[token] = i
+
+    self.assertAllEqual(
+        tokenization.convert_tokens_to_ids(
+            vocab, ["un", "##want", "##ed", "runn", "##ing"]), [7, 4, 5, 8, 9])
+
+  def test_is_whitespace(self):
+    self.assertTrue(tokenization._is_whitespace(u" "))
+    self.assertTrue(tokenization._is_whitespace(u"\t"))
+    self.assertTrue(tokenization._is_whitespace(u"\r"))
+    self.assertTrue(tokenization._is_whitespace(u"\n"))
+    self.assertTrue(tokenization._is_whitespace(u"\u00A0"))
+
+    self.assertFalse(tokenization._is_whitespace(u"A"))
+    self.assertFalse(tokenization._is_whitespace(u"-"))
+
+  def test_is_control(self):
+    self.assertTrue(tokenization._is_control(u"\u0005"))
+
+    self.assertFalse(tokenization._is_control(u"A"))
+    self.assertFalse(tokenization._is_control(u" "))
+    self.assertFalse(tokenization._is_control(u"\t"))
+    self.assertFalse(tokenization._is_control(u"\r"))
+
+  def test_is_punctuation(self):
+    self.assertTrue(tokenization._is_punctuation(u"-"))
+    self.assertTrue(tokenization._is_punctuation(u"$"))
+    self.assertTrue(tokenization._is_punctuation(u"`"))
+    self.assertTrue(tokenization._is_punctuation(u"."))
+
+    self.assertFalse(tokenization._is_punctuation(u"A"))
+    self.assertFalse(tokenization._is_punctuation(u" "))
+
+
+if __name__ == "__main__":
+  tf.test.main()