def _get_masked_lm_output(self, inputs: pretrain_data.Inputs, model):
"""Masked language modeling softmax layer."""
masked_lm_weights = inputs.masked_lm_weights
with tf.variable_scope("generator_predictions"):
if self._config.uniform_generator:
logits = tf.zeros(self._bert_config.vocab_size)
logits_tiled = tf.zeros(
modeling.get_shape_list(inputs.masked_lm_ids) +
[self._bert_config.vocab_size])
logits_tiled += tf.reshape(
logits, [1, 1, self._bert_config.vocab_size])
logits = logits_tiled
else:
relevant_hidden = pretrain_helpers.gather_positions(
model.get_sequence_output(), inputs.masked_lm_positions)
hidden = tf.layers.dense(
relevant_hidden,
units=modeling.get_shape_list(
model.get_embedding_table())[-1],
activation=modeling.get_activation(
self._bert_config.hidden_act),
kernel_initializer=modeling.create_initializer(
self._bert_config.initializer_range))
hidden = modeling.layer_norm(hidden)
output_bias = tf.get_variable(
"output_bias",
shape=[self._bert_config.vocab_size],
initializer=tf.zeros_initializer())
logits = tf.matmul(hidden,
model.get_embedding_table(),
transpose_b=True)
logits = tf.nn.bias_add(logits, output_bias)
oh_labels = tf.one_hot(inputs.masked_lm_ids,
depth=self._bert_config.vocab_size,
dtype=tf.float32)
probs = tf.nn.softmax(logits)
log_probs = tf.nn.log_softmax(logits)
label_log_probs = -tf.reduce_sum(log_probs * oh_labels, axis=-1)
numerator = tf.reduce_sum(inputs.masked_lm_weights *
label_log_probs)
denominator = tf.reduce_sum(masked_lm_weights) + 1e-6
loss = numerator / denominator
preds = tf.argmax(log_probs, axis=-1, output_type=tf.int32)
MLMOutput = collections.namedtuple(
"MLMOutput",
["logits", "probs", "loss", "per_example_loss", "preds"])
return MLMOutput(logits=logits,
probs=probs,
per_example_loss=label_log_probs,
loss=loss,
preds=preds)
def scatter_update(sequence, updates, positions):
"""Scatter-update a sequence.
Args:
sequence: A [batch_size, seq_len] or [batch_size, seq_len, depth] tensor
updates: A tensor of size batch_size*seq_len(*depth)
positions: A [batch_size, n_positions] tensor
Returns: A tuple of two tensors. First is a [batch_size, seq_len] or
[batch_size, seq_len, depth] tensor of "sequence" with elements at
"positions" replaced by the values at "updates." Updates to index 0 are
ignored. If there are duplicated positions the update is only applied once.
Second is a [batch_size, seq_len] mask tensor of which inputs were updated.
"""
shape = modeling.get_shape_list(sequence, expected_rank=[2, 3])
depth_dimension = (len(shape) == 3)
if depth_dimension:
B, L, D = shape
else:
B, L = shape
D = 1
sequence = tf.expand_dims(sequence, -1)
N = modeling.get_shape_list(positions)[1]
shift = tf.expand_dims(L * tf.range(B), -1)
flat_positions = tf.reshape(positions + shift, [-1, 1])
flat_updates = tf.reshape(updates, [-1, D])
updates = tf.scatter_nd(flat_positions, flat_updates, [B * L, D])
updates = tf.reshape(updates, [B, L, D])
flat_updates_mask = tf.ones([B * N], tf.int32)
updates_mask = tf.scatter_nd(flat_positions, flat_updates_mask, [B * L])
updates_mask = tf.reshape(updates_mask, [B, L])
not_first_token = tf.concat(
[tf.zeros((B, 1), tf.int32),
tf.ones((B, L - 1), tf.int32)], -1)
updates_mask *= not_first_token
updates_mask_3d = tf.expand_dims(updates_mask, -1)
# account for duplicate positions
if sequence.dtype == tf.float32:
updates_mask_3d = tf.cast(updates_mask_3d, tf.float32)
updates /= tf.maximum(1.0, updates_mask_3d)
else:
assert sequence.dtype == tf.int32
updates = tf.math.floordiv(updates, tf.maximum(1, updates_mask_3d))
updates_mask = tf.minimum(updates_mask, 1)
updates_mask_3d = tf.minimum(updates_mask_3d, 1)
updated_sequence = (((1 - updates_mask_3d) * sequence) +
(updates_mask_3d * updates))
if not depth_dimension:
updated_sequence = tf.squeeze(updated_sequence, -1)
return updated_sequence, updates_mask
def _get_entropy_output(self, inputs: pretrain_data.Inputs, model):
"""Masked language modeling softmax layer."""
with tf.variable_scope("cls/predictions", reuse=tf.AUTO_REUSE):
hidden = tf.layers.dense(
model.get_sequence_output(),
units=modeling.get_shape_list(model.get_embedding_table())[-1],
activation=modeling.get_activation(
self._bert_config.hidden_act),
kernel_initializer=modeling.create_initializer(
self._bert_config.initializer_range))
hidden = modeling.layer_norm(hidden)
output_bias = tf.get_variable("output_bias",
shape=[self._bert_config.vocab_size],
initializer=tf.zeros_initializer())
logits = tf.matmul(hidden,
model.get_embedding_table(),
transpose_b=True)
logits = tf.nn.bias_add(logits, output_bias)
probs = tf.nn.softmax(logits)
log_probs = tf.nn.log_softmax(logits)
entropy = -tf.reduce_sum(log_probs * probs, axis=[2])
EntropyOutput = collections.namedtuple(
"EntropyOutput", ["logits", "probs", "log_probs", "entropy"])
return EntropyOutput(logits=logits,
probs=probs,
log_probs=log_probs,
entropy=entropy)
def gather_positions(sequence, positions):
"""Gathers the vectors at the specific positions over a minibatch.
Args:
sequence: A [batch_size, seq_length] or
[batch_size, seq_length, depth] tensor of values
positions: A [batch_size, n_positions] tensor of indices
Returns: A [batch_size, n_positions] or
[batch_size, n_positions, depth] tensor of the values at the indices
"""
shape = modeling.get_shape_list(sequence, expected_rank=[2, 3])
depth_dimension = (len(shape) == 3)
if depth_dimension:
B, L, D = shape
else:
B, L = shape
D = 1
sequence = tf.expand_dims(sequence, -1)
position_shift = tf.expand_dims(L * tf.range(B), -1)
flat_positions = tf.reshape(positions + position_shift, [-1])
flat_sequence = tf.reshape(sequence, [B * L, D])
gathered = tf.gather(flat_sequence, flat_positions)
if depth_dimension:
return tf.reshape(gathered, [B, -1, D])
else:
return tf.reshape(gathered, [B, -1])
def sample_from_softmax(logits, disallow=None):
if disallow is not None:
logits -= 1000.0 * disallow
uniform_noise = tf.random.uniform(
modeling.get_shape_list(logits), minval=0, maxval=1)
gumbel_noise = -tf.log(-tf.log(uniform_noise + 1e-9) + 1e-9)
return tf.one_hot(tf.argmax(tf.nn.softmax(logits + gumbel_noise), -1,
output_type=tf.int32), logits.shape[-1])
def sample_from_top_k(logits,
temperature,
disallow=None,
straight_through=False,
k=20):
print(logits, '===========')
logits_shape = modeling.get_shape_list(logits, expected_rank=[2, 3])
depth_dimension = (len(logits_shape) == 3)
if depth_dimension:
reshape_logits = tf.reshape(logits, [-1, logits_shape[-1]])
else:
reshape_logits = logits
print(reshape_logits, '======')
reshape_logits_shape = modeling.get_shape_list(reshape_logits,
expected_rank=[2])
batch = reshape_logits_shape[0]
values, _ = tf.nn.top_k(reshape_logits, k=k)
min_values = values[:, -1, tf.newaxis]
reshape_topk_logits = tf.where(
reshape_logits < min_values,
tf.ones_like(reshape_logits, dtype=logits.dtype) * -1e10,
reshape_logits,
)
topk_logits = tf.reshape(reshape_topk_logits, logits_shape)
if disallow is not None:
topk_logits -= 1e10 * disallow
uniform_noise = tf.random.uniform(modeling.get_shape_list(topk_logits),
minval=0,
maxval=1)
gumbel_noise = -tf.log(-tf.log(uniform_noise + 1e-9) + 1e-9)
gumbel_logits = (topk_logits + gumbel_noise) / temperature
gumbel_probs = tf.nn.softmax(gumbel_logits)
hard_token_ids = tf.one_hot(
tf.argmax(gumbel_probs, axis=-1, output_type=tf.int32),
topk_logits.shape[-1])
if straight_through:
gumbel_dense = tf.stop_gradient(hard_token_ids -
gumbel_probs) + gumbel_probs
else:
gumbel_dense = gumbel_probs
return gumbel_dense
def __init__(self, config: configure_finetuning.FinetuningConfig, tasks,
is_training, features, num_train_steps):
# Create a shared transformer encoder
bert_config = training_utils.get_bert_config(config)
self.bert_config = bert_config
if config.debug:
bert_config.num_hidden_layers = 3
bert_config.hidden_size = 144
bert_config.intermediate_size = 144 * 4
bert_config.num_attention_heads = 4
# multi-choice mrc
if any([isinstance(x, qa_tasks.MQATask) for x in tasks]):
seq_len = config.max_seq_length
assert seq_len <= bert_config.max_position_embeddings
bs, total_len = modeling.get_shape_list(features["input_ids"],
expected_rank=2)
to_shape = [
bs * config.max_options_num * config.evidences_top_k, seq_len
]
bert_model = modeling.BertModel(
bert_config=bert_config,
is_training=is_training,
input_ids=tf.reshape(features["input_ids"], to_shape),
input_mask=tf.reshape(features["input_mask"], to_shape),
token_type_ids=tf.reshape(features["segment_ids"], to_shape),
use_one_hot_embeddings=config.use_tpu,
embedding_size=config.embedding_size)
else:
assert config.max_seq_length <= bert_config.max_position_embeddings
bert_model = modeling.BertModel(
bert_config=bert_config,
is_training=is_training,
input_ids=features["input_ids"],
input_mask=features["input_mask"],
token_type_ids=features["segment_ids"],
use_one_hot_embeddings=config.use_tpu,
embedding_size=config.embedding_size)
percent_done = (
tf.cast(tf.train.get_or_create_global_step(), tf.float32) /
tf.cast(num_train_steps, tf.float32))
# Add specific tasks
self.outputs = {"task_id": features["task_id"]}
losses = []
for task in tasks:
with tf.variable_scope("task_specific/" + task.name):
task_losses, task_outputs = task.get_prediction_module(
bert_model, features, is_training, percent_done)
losses.append(task_losses)
self.outputs[task.name] = task_outputs
self.loss = tf.reduce_sum(
tf.stack(losses, -1) *
tf.one_hot(features["task_id"], len(config.task_names)))
def _get_masked_lm_output(inputs, model):
"""Masked language modeling softmax layer."""
with tf.variable_scope("generator_predictions"):
logits = tf.zeros(21228)
logits_tiled = tf.zeros(
modeling.get_shape_list(inputs.masked_lm_ids) + [21228])
logits_tiled += tf.reshape(logits, [1, 1, 21228])
logits = logits_tiled
return get_softmax_output(logits, inputs.masked_lm_ids,
inputs.masked_lm_weights, 21228)
def get_prediction_module(self, bert_model, features, is_training,
percent_done):
final_hidden = bert_model.get_pooled_output()
# bs * options_num * top_k, hidden_dim
final_hidden_shape = modeling.get_shape_list(final_hidden, expected_rank=2)
# bs, options_num * top_k * seq_len
input_ids_shape = modeling.get_shape_list(features["input_ids"], expected_rank=2)
batch_size = input_ids_shape[0]
hidden_dim = final_hidden_shape[1]
final_hidden_reshape = tf.reshape(final_hidden, [batch_size, self.config.max_options_num,
self.config.evidences_top_k * hidden_dim])
# def single(hidden, mask, y):
# logits = tf.squeeze(tf.layers.dense(hidden, 1), -1)
# mask = mask[:self.config.max_options_num]
# y = y[:self.config.max_options_num]
# logits_masked = logits + 1e8 * (mask - 1)
# loss = tf.nn.softmax_cross_entropy_with_logits(labels=y, logits=logits_masked)
# return logits_masked, loss
#
# def combination_single(hidden, mask, y):
# logits = tf.squeeze(tf.layers.dense(hidden, 1), -1) # todo: share or not ?
# logits = tf.layers.dense(logits, 2 ** self.config.max_options_num)
# logits_masked = logits + 1e8 * (mask - 1)
# loss = tf.nn.softmax_cross_entropy_with_logits(labels=y, logits=logits_masked)
# return logits_masked, loss
# logits, loss = tf.cond()
logits = tf.squeeze(tf.layers.dense(final_hidden_reshape, 1), -1)
loss1 = tf.nn.sigmoid_cross_entropy_with_logits(labels=tf.to_float(features[self.name + "_answer_ids_raw"]), logits=logits)
loss1 = tf.reduce_mean(loss1, axis=-1)
logits = tf.layers.dense(logits, 2 ** self.config.max_options_num)
logits_masked = logits + 1e8 * tf.to_float(features[self.name + "_answer_mask"] - 1)
loss = tf.nn.softmax_cross_entropy_with_logits(labels=features[self.name + "_answer_ids"], logits=logits)
loss = loss * 0.2 + loss1 * 0.8
return loss, dict(
loss=loss,
logits=logits_masked,
eid=features[self.name + "_eid"],
)
def get_token_logits(input_reprs, embedding_table, bert_config):
hidden = tf.layers.dense(
input_reprs,
units=modeling.get_shape_list(embedding_table)[-1],
activation=modeling.get_activation(bert_config.hidden_act),
kernel_initializer=modeling.create_initializer(
bert_config.initializer_range))
hidden = modeling.layer_norm(hidden)
output_bias = tf.get_variable("output_bias",
shape=[bert_config.vocab_size],
initializer=tf.zeros_initializer())
logits = tf.matmul(hidden, embedding_table, transpose_b=True)
logits = tf.nn.bias_add(logits, output_bias)
return logits
def gather_indexes(sequence_tensor, positions):
"""Gathers the vectors at the specific positions over a minibatch."""
sequence_shape = modeling.get_shape_list(sequence_tensor, expected_rank=3)
batch_size = sequence_shape[0]
seq_length = sequence_shape[1]
width = sequence_shape[2]
flat_offsets = tf.reshape(
tf.range(0, batch_size, dtype=tf.int32) * seq_length, [-1, 1])
flat_positions = tf.reshape(positions + flat_offsets, [-1])
flat_sequence_tensor = tf.reshape(sequence_tensor,
[batch_size * seq_length, width])
output_tensor = tf.gather(flat_sequence_tensor, flat_positions)
return output_tensor
def _build_teacher(self,
states,
inputs: pretrain_data.Inputs,
is_training,
name="teacher",
reuse=False,
**kwargs):
"""Build teacher network to estimate token score."""
input_shape = get_shape_list(states, expected_rank=3)
prev_output = states
hidden_size = self._teacher_config.hidden_size
num_hidden_layers = self._teacher_config.num_hidden_layers
if is_training:
hidden_dropout_prob = self._teacher_config.hidden_dropout_prob
else:
hidden_dropout_prob = 0.0
with tf.variable_scope("teacher", reuse=reuse):
for layer_idx in range(num_hidden_layers):
with tf.variable_scope("layer_%d" % layer_idx):
layer_input = prev_output
layer_output = tf.layers.dense(
layer_input,
hidden_size,
activation=get_activation("gelu"),
kernel_initializer=create_initializer(
self._teacher_config.initializer_range))
layer_output = dropout(layer_output, hidden_dropout_prob)
layer_output = layer_norm(layer_output)
prev_output = layer_output
sequence_output = prev_output
with tf.variable_scope("bernoulli"):
with tf.variable_scope("transform"):
logits = tf.layers.dense(
sequence_output,
units=1,
kernel_initializer=create_initializer(
self._teacher_config.initializer_range))
action_probs = tf.nn.sigmoid(logits)
action_probs = tf.squeeze(action_probs)
TeacherOutput = collections.namedtuple("TeacherOutput",
["action_probs"])
return TeacherOutput(action_probs=action_probs)
def _get_masked_lm_output(self, inputs: pretrain_data.Inputs, model):
"""Masked language modeling softmax layer."""
with tf.variable_scope("generator_predictions"):
if self._config.uniform_generator:
logits = tf.zeros(self._bert_config.vocab_size)
logits_tiled = tf.zeros(
modeling.get_shape_list(inputs.masked_lm_ids) +
[self._bert_config.vocab_size])
logits_tiled += tf.reshape(
logits, [1, 1, self._bert_config.vocab_size])
logits = logits_tiled
else:
relevant_reprs = pretrain_helpers.gather_positions(
model.get_sequence_output(), inputs.masked_lm_positions)
logits = get_token_logits(relevant_reprs,
model.get_embedding_table(),
self._bert_config)
return get_softmax_output(logits, inputs.masked_lm_ids,
inputs.masked_lm_weights,
self._bert_config.vocab_size)
def _get_autoencoder_output(self, inputs: pretrain_data.Inputs, model):
"""Auto-Encoder softmax layer."""
with tf.variable_scope("autoencoder_predictions"):
relevant_hidden = model.get_sequence_output()
hidden = tf.layers.dense(
relevant_hidden,
units=modeling.get_shape_list(model.get_embedding_table())[-1],
activation=modeling.get_activation(
self._bert_config.hidden_act),
kernel_initializer=modeling.create_initializer(
self._bert_config.initializer_range))
hidden = modeling.layer_norm(hidden)
output_bias = tf.get_variable("output_bias",
shape=[self._bert_config.vocab_size],
initializer=tf.zeros_initializer())
logits = tf.matmul(hidden,
model.get_embedding_table(),
transpose_b=True)
logits = tf.nn.bias_add(logits, output_bias)
oh_labels = tf.one_hot(inputs.input_ids,
depth=self._bert_config.vocab_size,
dtype=tf.float32)
probs = tf.nn.softmax(logits)
log_probs = tf.nn.log_softmax(logits)
label_log_probs = -tf.reduce_sum(log_probs * oh_labels, axis=-1)
numerator = tf.reduce_sum(inputs.input_mask * label_log_probs)
denominator = tf.reduce_sum(inputs.input_mask) + 1e-6
loss = numerator / denominator
preds = tf.argmax(log_probs, axis=-1, output_type=tf.int32)
AEOutput = collections.namedtuple(
"AEOutput",
["logits", "probs", "loss", "per_example_loss", "preds"])
return AEOutput(logits=logits,
probs=probs,
per_example_loss=label_log_probs,
loss=loss,
preds=preds)
def sample_from_softmax(logits,
temperature,
disallow=None,
straight_through=False):
if disallow is not None:
logits -= 1000.0 * disallow
uniform_noise = tf.random.uniform(modeling.get_shape_list(logits),
minval=0,
maxval=1)
gumbel_noise = -tf.log(-tf.log(uniform_noise + 1e-9) + 1e-9)
gumbel_logits = (logits + gumbel_noise) / temperature
gumbel_probs = tf.nn.softmax(gumbel_logits)
hard_token_ids = tf.one_hot(
tf.argmax(gumbel_probs, axis=-1, output_type=tf.int32),
logits.shape[-1])
if straight_through:
gumbel_dense = tf.stop_gradient(hard_token_ids -
gumbel_probs) + gumbel_probs
else:
gumbel_dense = gumbel_probs
return gumbel_dense
def _sample_masking_subset(self, inputs: pretrain_data.Inputs,
action_probs):
#calculate shifted action_probs
input_mask = inputs.input_mask
segment_ids = inputs.segment_ids
input_ids = inputs.input_ids
shape = modeling.get_shape_list(input_ids, expected_rank=2)
batch_size = shape[0]
max_seq_len = shape[1]
def _remove_special_token(elems):
action_prob = tf.cast(elems[0], tf.float32)
segment = tf.cast(elems[1], tf.int32)
input = tf.cast(elems[2], tf.int32)
mask = tf.cast(elems[3], tf.int32)
seq_len = tf.reduce_sum(mask)
seg1_len = seq_len - tf.reduce_sum(segment)
seq1_idx = tf.range(start=1, limit=seg1_len - 1, dtype=tf.int32)
seq2_limit = tf.math.maximum(seg1_len, seq_len - 1)
seq2_idx = tf.range(start=seg1_len,
limit=seq2_limit,
dtype=tf.int32)
mask_idx = tf.range(start=seq_len,
limit=max_seq_len,
dtype=tf.int32)
index_tensor = tf.concat([seq1_idx, seq2_idx, mask_idx], axis=0)
seq1_prob = action_prob[1:seg1_len - 1]
seq2_prob = action_prob[seg1_len:seq2_limit]
mask_prob = tf.ones_like(mask_idx, dtype=tf.float32) * 1e-20
cleaned_action_prob = tf.concat([seq1_prob, seq2_prob, mask_prob],
axis=0)
cleaned_mask = tf.concat([
mask[1:seg1_len - 1], mask[seg1_len:seq_len - 1],
mask[seq_len:max_seq_len]
],
axis=0)
cleaned_input = tf.concat([
input[1:seg1_len - 1], input[seg1_len:seq_len - 1],
input[seq_len:max_seq_len]
],
axis=0)
cleaned_action_prob = cleaned_action_prob[0:max_seq_len - 3]
index_tensor = index_tensor[0:max_seq_len - 3]
cleaned_input = cleaned_input[0:max_seq_len - 3]
cleaned_mask = cleaned_mask[0:max_seq_len - 3]
return (cleaned_action_prob, index_tensor, cleaned_input,
cleaned_mask)
# Remove CLS and SEP action probs
elems = tf.stack([
action_probs,
tf.cast(segment_ids, tf.float32),
tf.cast(input_ids, tf.float32),
tf.cast(input_mask, tf.float32)
], 1)
cleaned_action_probs, index_tensors, cleaned_inputs, cleaned_input_mask = tf.map_fn(
_remove_special_token,
elems,
dtype=(tf.float32, tf.int32, tf.int32, tf.int32),
parallel_iterations=1)
logZ, log_prob = self._calculate_partition_table(
cleaned_input_mask, cleaned_action_probs,
self._config.max_predictions_per_seq)
samples, log_q = self._sampling_a_subset(
logZ, log_prob, self._config.max_predictions_per_seq)
# Collect masked_lm_ids and masked_lm_positions
zero_values = tf.zeros_like(index_tensors, tf.int32)
selected_position = tf.where(tf.equal(samples, 1), index_tensors,
zero_values)
masked_lm_positions, _ = tf.nn.top_k(
selected_position,
self._config.max_predictions_per_seq,
sorted=False)
# Get the ids of the masked-out tokens
shift = tf.expand_dims(max_seq_len * tf.range(batch_size), -1)
flat_positions = tf.reshape(masked_lm_positions + shift, [-1, 1])
masked_lm_ids = tf.gather_nd(tf.reshape(input_ids, [-1]),
flat_positions)
masked_lm_ids = tf.reshape(masked_lm_ids, [batch_size, -1])
# Update the input ids
replaced_prob = tf.random.uniform(
[batch_size, self._config.max_predictions_per_seq])
replace_with_mask_positions = masked_lm_positions * tf.cast(
tf.less(replaced_prob, 0.85), tf.int32)
inputs_ids, _ = scatter_update(
inputs.input_ids,
tf.fill([batch_size, self._config.max_predictions_per_seq],
self._vocab["[MASK]"]), replace_with_mask_positions)
# Replace with random tokens
replace_with_random_positions = masked_lm_positions * tf.cast(
tf.greater(replaced_prob, 0.925), tf.int32)
random_tokens = tf.random.uniform(
[batch_size, self._config.max_predictions_per_seq],
minval=0,
maxval=len(self._vocab),
dtype=tf.int32)
inputs_ids, _ = scatter_update(inputs_ids, random_tokens,
replace_with_random_positions)
masked_lm_weights = tf.ones_like(masked_lm_ids, tf.float32)
inv_vocab = self._inv_vocab
# Apply mask on input
if self._config.debug:
def pretty_print(inputs_ids, masked_lm_ids, masked_lm_positions,
masked_lm_weights, tag_ids):
debug_inputs = Inputs(input_ids=inputs_ids,
input_mask=None,
segment_ids=None,
masked_lm_positions=masked_lm_positions,
masked_lm_ids=masked_lm_ids,
masked_lm_weights=masked_lm_weights,
tag_ids=tag_ids)
pretrain_data.print_tokens(debug_inputs, inv_vocab)
## TODO: save to the mask choice
return inputs_ids, masked_lm_ids, masked_lm_positions, masked_lm_weights
mask_shape = masked_lm_ids.get_shape()
inputs_ids, masked_lm_ids, masked_lm_positions, masked_lm_weights = \
tf.py_func(pretty_print, [inputs_ids, masked_lm_ids, masked_lm_positions, masked_lm_weights, inputs.tag_ids],
(tf.int32, tf.int32, tf.int32, tf.float32))
inputs_ids.set_shape(inputs.input_ids.get_shape())
masked_lm_ids.set_shape(mask_shape)
masked_lm_positions.set_shape(mask_shape)
masked_lm_weights.set_shape(mask_shape)
masked_input = pretrain_data.get_updated_inputs(
inputs,
input_ids=tf.stop_gradient(input_ids),
masked_lm_positions=tf.stop_gradient(masked_lm_positions),
masked_lm_ids=tf.stop_gradient(masked_lm_ids),
masked_lm_weights=tf.stop_gradient(masked_lm_weights),
tag_ids=inputs.tag_ids)
return log_q, masked_input
def mask(config: configure_pretraining.PretrainingConfig,
inputs: pretrain_data.Inputs, mask_prob, proposal_distribution=1.0,
disallow_from_mask=None, already_masked=None):
"""Implementation of dynamic masking. The optional arguments aren't needed for
BERT/ELECTRA and are from early experiments in "strategically" masking out
tokens instead of uniformly at random.
Args:
config: configure_pretraining.PretrainingConfig
inputs: pretrain_data.Inputs containing input input_ids/input_mask
mask_prob: percent of tokens to mask
proposal_distribution: for non-uniform masking can be a [B, L] tensor
of scores for masking each position.
disallow_from_mask: a boolean tensor of [B, L] of positions that should
not be masked out
already_masked: a boolean tensor of [B, N] of already masked-out tokens
for multiple rounds of masking
Returns: a pretrain_data.Inputs with masking added
"""
# Get the batch size, sequence length, and max masked-out tokens
N = config.max_predictions_per_seq
B, L = modeling.get_shape_list(inputs.input_ids)
# Find indices where masking out a token is allowed
tokenizer = tokenization.FullTokenizer(
config.vocab_file, do_lower_case=config.do_lower_case)
vocab = tokenizer.vocab
inv_vocab = tokenizer.inv_vocab
candidates_mask = _get_candidates_mask(inputs, vocab, disallow_from_mask)
# Set the number of tokens to mask out per example
num_tokens = tf.cast(tf.reduce_sum(inputs.input_mask, -1), tf.float32)
num_to_predict = tf.maximum(1, tf.minimum(
N, tf.cast(tf.round(num_tokens * mask_prob), tf.int32)))
masked_lm_weights = tf.cast(tf.sequence_mask(num_to_predict, N), tf.float32)
if already_masked is not None:
masked_lm_weights *= (1 - already_masked)
# Get a probability of masking each position in the sequence
candidate_mask_float = tf.cast(candidates_mask, tf.float32)
if config.masking_strategy == RAND_STRATEGY or config.masking_strategy == MIX_ADV_STRATEGY:
sample_prob = (proposal_distribution * candidate_mask_float)
elif config.masking_strategy == POS_STRATEGY:
unfavor_pos_mask = _get_unfavor_pos_mask(inputs)
unfavor_pos_mask_float = tf.cast(unfavor_pos_mask, tf.float32)
prefer_pos_mask_float = 1 - unfavor_pos_mask_float
# prefered pos have 80% propabiblity, not preferred ones have 20% probability
# proposal_distribution = prefer_pos_mask_float
proposal_distribution = 0.95 * prefer_pos_mask_float + 0.05
sample_prob = (proposal_distribution * candidate_mask_float)
elif config.masking_strategy == ENTROPY_STRATEGY:
sample_prob = (proposal_distribution * candidate_mask_float)
elif config.masking_strategy == MIX_POS_STRATEGY:
rand_sample_prob = (proposal_distribution * candidate_mask_float)
unfavor_pos_mask = _get_unfavor_pos_mask(inputs)
unfavor_pos_mask_float = tf.cast(unfavor_pos_mask, tf.float32)
prefer_pos_mask_float = 1 - unfavor_pos_mask_float
# prefered pos have 80% propabiblity, not preferred ones have 20% probability
# proposal_distribution = prefer_pos_mask_float
proposal_distribution = 0.95 * prefer_pos_mask_float + 0.05
pos_sample_prob = (proposal_distribution * candidate_mask_float)
strategy_prob = tf.random.uniform([B])
strategy_prob = tf.expand_dims(tf.cast(tf.greater(strategy_prob,0.5), tf.float32),1)
strategy_prob = tf.tile(strategy_prob, [1,L])
sample_prob = rand_sample_prob * strategy_prob + pos_sample_prob * (1 - strategy_prob)
elif config.masking_strategy == MIX_ENTROPY_STRATEGY:
rand_sample_prob = (proposal_distribution * candidate_mask_float)
entropy_sample_prob = (proposal_distribution * candidate_mask_float)
strategy_prob = tf.random.uniform([B])
strategy_prob = tf.expand_dims(tf.cast(tf.greater(strategy_prob,0.5), tf.float32),1)
strategy_prob = tf.tile(strategy_prob, [1, L])
sample_prob = rand_sample_prob * strategy_prob + entropy_sample_prob * (1 - strategy_prob)
else:
raise ValueError("{} strategy is not supported".format(config.masking_strategy))
sample_prob /= tf.reduce_sum(sample_prob, axis=-1, keepdims=True)
# Sample the positions to mask out
sample_prob = tf.stop_gradient(sample_prob)
sample_logits = tf.log(sample_prob)
masked_lm_positions = tf.random.categorical(
sample_logits, N, dtype=tf.int32)
masked_lm_positions *= tf.cast(masked_lm_weights, tf.int32)
# Get the ids of the masked-out tokens
shift = tf.expand_dims(L * tf.range(B), -1)
flat_positions = tf.reshape(masked_lm_positions + shift, [-1, 1])
masked_lm_ids = tf.gather_nd(tf.reshape(inputs.input_ids, [-1]),
flat_positions)
masked_lm_ids = tf.reshape(masked_lm_ids, [B, -1])
masked_lm_ids *= tf.cast(masked_lm_weights, tf.int32)
# Update the input ids
replace_prob = tf.random.uniform([B, N])
replace_with_mask_positions = masked_lm_positions * tf.cast(
tf.less(replace_prob, 0.85), tf.int32)
inputs_ids, _ = scatter_update(
inputs.input_ids, tf.fill([B, N], vocab["[MASK]"]),
replace_with_mask_positions)
# Replace with random tokens
replace_with_random_positions = masked_lm_positions * tf.cast(
tf.greater(replace_prob, 0.925), tf.int32)
random_tokens = tf.random.uniform([B,N], minval=0, maxval=len(vocab), dtype=tf.int32)
inputs_ids, _ = scatter_update(
inputs_ids, random_tokens,
replace_with_random_positions)
if config.debug:
def pretty_print(inputs_ids, masked_lm_ids, masked_lm_positions, masked_lm_weights, tag_ids):
debug_inputs = Inputs(
input_ids=inputs_ids,
input_mask=None,
segment_ids=None,
masked_lm_positions=masked_lm_positions,
masked_lm_ids=masked_lm_ids,
masked_lm_weights=masked_lm_weights,
tag_ids = tag_ids)
pretrain_data.print_tokens(debug_inputs, inv_vocab)
## TODO: save to the mask choice
return inputs_ids, masked_lm_ids, masked_lm_positions, masked_lm_weights
mask_shape = masked_lm_ids.get_shape()
inputs_ids, masked_lm_ids, masked_lm_positions, masked_lm_weights = \
tf.py_func(pretty_print,[inputs_ids, masked_lm_ids, masked_lm_positions, masked_lm_weights, inputs.tag_ids],
(tf.int32, tf.int32, tf.int32, tf.float32))
inputs_ids.set_shape(inputs.input_ids.get_shape())
masked_lm_ids.set_shape(mask_shape)
masked_lm_positions.set_shape(mask_shape)
masked_lm_weights.set_shape(mask_shape)
return pretrain_data.get_updated_inputs(
inputs,
input_ids=tf.stop_gradient(inputs_ids),
masked_lm_positions=masked_lm_positions,
masked_lm_ids=masked_lm_ids,
masked_lm_weights=masked_lm_weights,
tag_ids = inputs.tag_ids
)
def mask(config: configure_pretraining.PretrainingConfig,
inputs: pretrain_data.Inputs, mask_prob, proposal_distribution=1.0,
disallow_from_mask=None, already_masked=None):
"""Implementation of dynamic masking. The optional arguments aren't needed for
BERT/ELECTRA and are from early experiments in "strategically" masking out
tokens instead of uniformly at random.
Args:
config: configure_pretraining.PretrainingConfig
inputs: pretrain_data.Inputs containing input input_ids/input_mask
mask_prob: percent of tokens to mask
proposal_distribution: for non-uniform masking can be a [B, L] tensor
of scores for masking each position.
disallow_from_mask: a boolean tensor of [B, L] of positions that should
not be masked out
already_masked: a boolean tensor of [B, N] of already masked-out tokens
for multiple rounds of masking
Returns: a pretrain_data.Inputs with masking added
"""
# Get the batch size, sequence length, and max masked-out tokens
N = config.max_predictions_per_seq
B, L = modeling.get_shape_list(inputs.input_ids)
# Find indices where masking out a token is allowed
vocab = tokenization.FullTokenizer(
config.vocab_file, do_lower_case=config.do_lower_case).vocab
candidates_mask = _get_candidates_mask(inputs, vocab, disallow_from_mask)
# Set the number of tokens to mask out per example
num_tokens = tf.cast(tf.reduce_sum(inputs.input_mask, -1), tf.float32)
num_to_predict = tf.maximum(1, tf.minimum(
N, tf.cast(tf.round(num_tokens * mask_prob), tf.int32)))
masked_lm_weights = tf.cast(tf.sequence_mask(num_to_predict, N), tf.float32)
if already_masked is not None:
masked_lm_weights *= (1 - already_masked)
# Get a probability of masking each position in the sequence
candidate_mask_float = tf.cast(candidates_mask, tf.float32)
sample_prob = (proposal_distribution * candidate_mask_float)
sample_prob /= tf.reduce_sum(sample_prob, axis=-1, keepdims=True)
# Sample the positions to mask out
sample_prob = tf.stop_gradient(sample_prob)
sample_logits = tf.log(sample_prob)
masked_lm_positions = tf.random.categorical(
sample_logits, N, dtype=tf.int32)
masked_lm_positions *= tf.cast(masked_lm_weights, tf.int32)
# Get the ids of the masked-out tokens
shift = tf.expand_dims(L * tf.range(B), -1)
flat_positions = tf.reshape(masked_lm_positions + shift, [-1, 1])
masked_lm_ids = tf.gather_nd(tf.reshape(inputs.input_ids, [-1]),
flat_positions)
masked_lm_ids = tf.reshape(masked_lm_ids, [B, -1])
masked_lm_ids *= tf.cast(masked_lm_weights, tf.int32)
# Update the input ids
replace_with_mask_positions = masked_lm_positions * tf.cast(
tf.less(tf.random.uniform([B, N]), 0.85), tf.int32)
inputs_ids, _ = scatter_update(
inputs.input_ids, tf.fill([B, N], vocab["[MASK]"]),
replace_with_mask_positions)
return pretrain_data.get_updated_inputs(
inputs,
input_ids=tf.stop_gradient(inputs_ids),
masked_lm_positions=masked_lm_positions,
masked_lm_ids=masked_lm_ids,
masked_lm_weights=masked_lm_weights
)
def get_prediction_module(self, bert_model, features, is_training,
percent_done):
final_hidden = bert_model.get_sequence_output()
final_hidden_shape = modeling.get_shape_list(final_hidden,
expected_rank=3)
batch_size = final_hidden_shape[0]
seq_length = final_hidden_shape[1]
answer_mask = tf.cast(features["input_mask"], tf.float32)
answer_mask *= tf.cast(features["segment_ids"], tf.float32)
answer_mask += tf.one_hot(0, seq_length)
start_logits = tf.squeeze(tf.layers.dense(final_hidden, 1), -1)
start_top_log_probs = tf.zeros([batch_size, self.config.beam_size])
start_top_index = tf.zeros([batch_size, self.config.beam_size],
tf.int32)
end_top_log_probs = tf.zeros(
[batch_size, self.config.beam_size, self.config.beam_size])
end_top_index = tf.zeros(
[batch_size, self.config.beam_size, self.config.beam_size],
tf.int32)
if self.config.joint_prediction:
start_logits += 1000.0 * (answer_mask - 1)
start_log_probs = tf.nn.log_softmax(start_logits)
start_top_log_probs, start_top_index = tf.nn.top_k(
start_log_probs, k=self.config.beam_size)
if not is_training:
# batch, beam, length, hidden
end_features = tf.tile(tf.expand_dims(final_hidden, 1),
[1, self.config.beam_size, 1, 1])
# batch, beam, length
start_index = tf.one_hot(start_top_index,
depth=seq_length,
axis=-1,
dtype=tf.float32)
# batch, beam, hidden
start_features = tf.reduce_sum(
tf.expand_dims(final_hidden, 1) *
tf.expand_dims(start_index, -1),
axis=-2)
# batch, beam, length, hidden
start_features = tf.tile(tf.expand_dims(start_features, 2),
[1, 1, seq_length, 1])
else:
start_index = tf.one_hot(features[self.name +
"_start_positions"],
depth=seq_length,
axis=-1,
dtype=tf.float32)
start_features = tf.reduce_sum(
tf.expand_dims(start_index, -1) * final_hidden, axis=1)
start_features = tf.tile(tf.expand_dims(start_features, 1),
[1, seq_length, 1])
end_features = final_hidden
final_repr = tf.concat([start_features, end_features], -1)
final_repr = tf.layers.dense(final_repr,
512,
activation=modeling.gelu,
name="qa_hidden")
# batch, beam, length (batch, length when training)
end_logits = tf.squeeze(tf.layers.dense(final_repr, 1),
-1,
name="qa_logits")
if is_training:
end_logits += 1000.0 * (answer_mask - 1)
else:
end_logits += tf.expand_dims(1000.0 * (answer_mask - 1), 1)
if not is_training:
end_log_probs = tf.nn.log_softmax(end_logits)
end_top_log_probs, end_top_index = tf.nn.top_k(
end_log_probs, k=self.config.beam_size)
end_logits = tf.zeros([batch_size, seq_length])
else:
end_logits = tf.squeeze(tf.layers.dense(final_hidden, 1), -1)
start_logits += 1000.0 * (answer_mask - 1)
end_logits += 1000.0 * (answer_mask - 1)
def compute_loss(logits, positions):
one_hot_positions = tf.one_hot(positions,
depth=seq_length,
dtype=tf.float32)
log_probs = tf.nn.log_softmax(logits, axis=-1)
loss = -tf.reduce_sum(one_hot_positions * log_probs, axis=-1)
return loss
start_positions = features[self.name + "_start_positions"]
end_positions = features[self.name + "_end_positions"]
start_loss = compute_loss(start_logits, start_positions)
end_loss = compute_loss(end_logits, end_positions)
losses = (start_loss + end_loss) / 2.0
answerable_logit = tf.zeros([batch_size])
if self.config.answerable_classifier:
final_repr = final_hidden[:, 0]
if self.config.answerable_uses_start_logits:
start_p = tf.nn.softmax(start_logits)
start_feature = tf.reduce_sum(tf.expand_dims(start_p, -1) *
final_hidden,
axis=1)
final_repr = tf.concat([final_repr, start_feature], -1)
final_repr = tf.layers.dense(final_repr,
512,
activation=modeling.gelu)
answerable_logit = tf.squeeze(tf.layers.dense(final_repr, 1), -1)
answerable_loss = tf.nn.sigmoid_cross_entropy_with_logits(
labels=tf.cast(features[self.name + "_is_impossible"],
tf.float32),
logits=answerable_logit)
losses += answerable_loss * self.config.answerable_weight
return losses, dict(
loss=losses,
start_logits=start_logits,
end_logits=end_logits,
answerable_logit=answerable_logit,
start_positions=features[self.name + "_start_positions"],
end_positions=features[self.name + "_end_positions"],
start_top_log_probs=start_top_log_probs,
start_top_index=start_top_index,
end_top_log_probs=end_top_log_probs,
end_top_index=end_top_index,
eid=features[self.name + "_eid"],
)
def get_prediction_module(self, bert_model, features, is_training,
percent_done):
final_hidden = bert_model.get_sequence_output()
# sgnet
# dep_mask_x = features[self.name + "_dep_mask_x"]
# dep_mask_y = features[self.name + "_dep_mask_y"]
# dep_mask_len = features[self.name + "_dep_mask_len"]
#
# def fn(xyz):
# x = xyz[0]
# y = xyz[1]
# length = xyz[2]
# x = x[:length]
# y = y[:length]
# st = tf.SparseTensor(indices=tf.cast(tf.transpose([x, y]), tf.int64),
# values=tf.ones_like(x, dtype=tf.float32),
# dense_shape=[self.config.max_seq_length, self.config.max_seq_length])
# dt = tf.sparse_tensor_to_dense(st)
# return dt
#
# dep_mask = tf.map_fn(fn, (dep_mask_x, dep_mask_y, dep_mask_len), dtype=tf.float32)
# dep_mask = features["squad_dep_mask"]
# dep_mask = tf.reshape(dep_mask, [-1, self.config.max_seq_length, self.config.max_seq_length])
# with tf.variable_scope("dependence"):
# bert_config = bert_model.config
# dep_att_output, _ = modeling.transformer_model(
# input_tensor=final_hidden,
# attention_mask=dep_mask,
# hidden_size=bert_config.hidden_size,
# num_hidden_layers=1,
# num_attention_heads=bert_config.num_attention_heads,
# intermediate_size=bert_config.intermediate_size,
# intermediate_act_fn=modeling.get_activation(bert_config.hidden_act),
# hidden_dropout_prob=bert_config.hidden_dropout_prob,
# attention_probs_dropout_prob=bert_config.attention_probs_dropout_prob,
# initializer_range=bert_config.initializer_range,
# do_return_all_layers=False)
# weight = tf.get_variable(name="weight", dtype=tf.float32, initializer=tf.zeros_initializer(),
# shape=(), trainable=True)
# weight = tf.sigmoid(weight)
# final_hidden = weight * final_hidden + (1 - weight) * dep_att_output
final_hidden_shape = modeling.get_shape_list(final_hidden,
expected_rank=3)
batch_size = final_hidden_shape[0]
seq_length = final_hidden_shape[1]
answer_mask = tf.cast(features["input_mask"], tf.float32)
answer_mask *= tf.cast(features["segment_ids"], tf.float32)
answer_mask += tf.one_hot(0, seq_length)
start_logits = tf.squeeze(tf.layers.dense(final_hidden, 1), -1)
start_top_log_probs = tf.zeros([batch_size, self.config.beam_size])
start_top_index = tf.zeros([batch_size, self.config.beam_size],
tf.int32)
end_top_log_probs = tf.zeros(
[batch_size, self.config.beam_size, self.config.beam_size])
end_top_index = tf.zeros(
[batch_size, self.config.beam_size, self.config.beam_size],
tf.int32)
if self.config.joint_prediction:
start_logits += 1000.0 * (answer_mask - 1)
start_log_probs = tf.nn.log_softmax(start_logits)
start_top_log_probs, start_top_index = tf.nn.top_k(
start_log_probs, k=self.config.beam_size)
if not is_training:
# batch, beam, length, hidden
end_features = tf.tile(tf.expand_dims(final_hidden, 1),
[1, self.config.beam_size, 1, 1])
# batch, beam, length
start_index = tf.one_hot(start_top_index,
depth=seq_length,
axis=-1,
dtype=tf.float32)
# batch, beam, hidden
start_features = tf.reduce_sum(
tf.expand_dims(final_hidden, 1) *
tf.expand_dims(start_index, -1),
axis=-2)
# batch, beam, length, hidden
start_features = tf.tile(tf.expand_dims(start_features, 2),
[1, 1, seq_length, 1])
else:
start_index = tf.one_hot(features[self.name +
"_start_positions"],
depth=seq_length,
axis=-1,
dtype=tf.float32)
start_features = tf.reduce_sum(
tf.expand_dims(start_index, -1) * final_hidden, axis=1)
start_features = tf.tile(tf.expand_dims(start_features, 1),
[1, seq_length, 1])
end_features = final_hidden
final_repr = tf.concat([start_features, end_features], -1)
final_repr = tf.layers.dense(final_repr,
512,
activation=modeling.gelu,
name="qa_hidden")
# batch, beam, length (batch, length when training)
end_logits = tf.squeeze(tf.layers.dense(final_repr, 1),
-1,
name="qa_logits")
if is_training:
end_logits += 1000.0 * (answer_mask - 1)
else:
end_logits += tf.expand_dims(1000.0 * (answer_mask - 1), 1)
if not is_training:
end_log_probs = tf.nn.log_softmax(end_logits)
end_top_log_probs, end_top_index = tf.nn.top_k(
end_log_probs, k=self.config.beam_size)
end_logits = tf.zeros([batch_size, seq_length])
else:
end_logits = tf.squeeze(tf.layers.dense(final_hidden, 1), -1)
start_logits += 1000.0 * (answer_mask - 1)
end_logits += 1000.0 * (answer_mask - 1)
def compute_loss(logits, positions):
one_hot_positions = tf.one_hot(positions,
depth=seq_length,
dtype=tf.float32)
log_probs = tf.nn.log_softmax(logits, axis=-1)
loss = -tf.reduce_sum(one_hot_positions * log_probs, axis=-1)
return loss
start_positions = features[self.name + "_start_positions"]
end_positions = features[self.name + "_end_positions"]
start_loss = compute_loss(start_logits, start_positions)
end_loss = compute_loss(end_logits, end_positions)
losses = (start_loss + end_loss) / 2.0
# plausible answer loss
plau_logits = tf.layers.dense(final_hidden, 2)
plau_logits = tf.reshape(plau_logits, [batch_size, seq_length, 2])
plau_logits = tf.transpose(plau_logits, [2, 0, 1])
unstacked_logits = tf.unstack(plau_logits, axis=0)
(plau_start_logits, plau_end_logits) = (unstacked_logits[0],
unstacked_logits[1])
plau_start_logits += 1000.0 * (answer_mask - 1)
plau_end_logits += 1000.0 * (answer_mask - 1)
plau_start_positions = features[self.name + "_plau_answer_start"]
plau_end_positions = features[self.name + "_plau_answer_end"]
plau_start_loss = compute_loss(plau_start_logits, plau_start_positions)
plau_end_loss = compute_loss(plau_end_logits, plau_end_positions)
losses += (plau_start_loss + plau_end_loss) / 2.0
# def compute_loss_for_plau(start_logits, end_logits, start_positions, end_positions, start_positions_true,
# alpha=1.0, beta=1.0):
# start_probs = tf.nn.softmax(start_logits)
# end_probs = tf.nn.softmax(end_logits)
# log_neg_start_probs = tf.log(tf.clip_by_value(1 - start_probs, 1e-30, 1))
# log_neg_end_probs = tf.log(tf.clip_by_value(1 - end_probs, 1e-30, 1))
# start_positions_mask = tf.cast(tf.sequence_mask(start_positions, maxlen=seq_length), tf.float32)
# end_positions_mask = tf.cast(tf.sequence_mask(end_positions + 1, maxlen=seq_length), tf.float32)
# positions_mask = end_positions_mask - start_positions_mask
# one_hot_positions = tf.one_hot(
# start_positions_true, depth=seq_length, dtype=tf.float32)
# positions_mask = positions_mask * (1 - one_hot_positions) # 忽略切出来的无答案
#
# # mask_0 = tf.zeros([batch_size, 1])
# # mask_1 = tf.ones([batch_size, seq_length - 1])
# # zero_mask = tf.concat([mask_0, mask_1], axis=1)
# # positions_mask = positions_mask * zero_mask
# loss1 = - tf.reduce_sum(positions_mask * log_neg_start_probs, axis=-1)
# loss1 = tf.reduce_mean(loss1)
# loss2 = - tf.reduce_sum(positions_mask * log_neg_end_probs, axis=-1)
# loss2 = tf.reduce_mean(loss2)
# return (loss1 * alpha + loss2 * beta) * 0.5
#
# plau_loss = compute_loss_for_plau(start_logits, end_logits,
# features[self.name + "_plau_answer_start"],
# features[self.name + "_plau_answer_end"],
# features[self.name + "_start_positions"], 1.0, 1.0)
# losses += plau_loss
answerable_logit = tf.zeros([batch_size])
if self.config.answerable_classifier:
final_repr = final_hidden[:, 0]
if self.config.answerable_uses_start_logits:
start_p = tf.nn.softmax(start_logits)
start_feature = tf.reduce_sum(tf.expand_dims(start_p, -1) *
final_hidden,
axis=1)
final_repr = tf.concat([final_repr, start_feature], -1)
final_repr = tf.layers.dense(final_repr,
512,
activation=modeling.gelu)
answerable_logit = tf.squeeze(tf.layers.dense(final_repr, 1), -1)
answerable_loss = tf.nn.sigmoid_cross_entropy_with_logits(
labels=tf.cast(features[self.name + "_is_impossible"],
tf.float32),
logits=answerable_logit)
losses += answerable_loss * self.config.answerable_weight
return losses, dict(
loss=losses,
start_logits=start_logits,
end_logits=end_logits,
answerable_logit=answerable_logit,
start_positions=features[self.name + "_start_positions"],
end_positions=features[self.name + "_end_positions"],
start_top_log_probs=start_top_log_probs,
start_top_index=start_top_index,
end_top_log_probs=end_top_log_probs,
end_top_index=end_top_index,
eid=features[self.name + "_eid"],
)
def _get_masked_lm_output(self, inputs: pretrain_data.Inputs, model):
"""Masked language modeling softmax layer."""
masked_lm_weights = inputs.masked_lm_weights
with tf.variable_scope("generator_predictions"):
if self._config.uniform_generator or self._config.identity_generator or self._config.heuristic_generator:
logits = tf.zeros(self._bert_config.vocab_size)
logits_tiled = tf.zeros(
modeling.get_shape_list(inputs.masked_lm_ids) +
[self._bert_config.vocab_size])
logits_tiled += tf.reshape(logits, [1, 1, self._bert_config.vocab_size])
logits = logits_tiled
else:
relevant_hidden = pretrain_helpers.gather_positions(
model.get_sequence_output(), inputs.masked_lm_positions)
hidden = tf.layers.dense(
relevant_hidden,
units=modeling.get_shape_list(model.get_embedding_table())[-1],
activation=modeling.get_activation(self._bert_config.hidden_act),
kernel_initializer=modeling.create_initializer(
self._bert_config.initializer_range))
hidden = modeling.layer_norm(hidden)
output_bias = tf.get_variable(
"output_bias",
shape=[self._bert_config.vocab_size],
initializer=tf.zeros_initializer())
logits = tf.matmul(hidden, model.get_embedding_table(),
transpose_b=True)
logits = tf.nn.bias_add(logits, output_bias)
oh_labels = tf.one_hot(
inputs.masked_lm_ids, depth=self._bert_config.vocab_size,
dtype=tf.float32)
probs = tf.nn.softmax(logits)
if self._config.identity_generator:
identity_logits = tf.zeros(self._bert_config.vocab_size)
identity_logits_tiled = tf.zeros(
modeling.get_shape_list(inputs.masked_lm_ids) +
[self._bert_config.vocab_size])
masked_identity_weights = tf.one_hot(inputs.masked_lm_ids, depth=self._bert_config.vocab_size, dtype=tf.float32)
identity_logits_tiled += 25.0 * masked_identity_weights
identity_logits_tiled += tf.reshape(identity_logits, [1, 1, self._bert_config.vocab_size])
identity_logits = identity_logits_tiled
identity_probs = tf.nn.softmax(identity_logits)
identity_weight = (self.global_step / tf.cast(self._config.num_train_steps, tf.float32)) * self._config.max_identity_weight
probs = probs * (1 - identity_weight) + identity_probs * identity_weight
logits = tf.math.log(probs) # softmax(log(probs)) = probs
elif self._config.heuristic_generator:
synonym_logits = tf.zeros(self._bert_config.vocab_size)
synonym_logits_tiled = tf.zeros(
modeling.get_shape_list(inputs.masked_lm_ids) +
[self._bert_config.vocab_size])
masked_synonym_weights = tf.reduce_sum(
tf.one_hot(inputs.masked_synonym_ids, depth=self._bert_config.vocab_size, dtype=tf.float32), -2)
padded_synonym_mask = tf.concat([tf.zeros([1]), tf.ones([self._bert_config.vocab_size - 1])], 0)
masked_synonym_weights *= tf.expand_dims(tf.expand_dims(padded_synonym_mask, 0), 0)
synonym_logits_tiled += 25.0 * masked_synonym_weights
synonym_logits_tiled += tf.reshape(synonym_logits, [1, 1, self._bert_config.vocab_size])
synonym_logits = synonym_logits_tiled
synonym_probs = tf.nn.softmax(synonym_logits)
if self._config.synonym_scheduler_type == 'linear':
synonym_weight = (self.global_step / tf.cast(self._config.num_train_steps, tf.float32)) * self._config.max_synonym_weight
probs = probs * (1 - synonym_weight) + synonym_probs * synonym_weight
logits = tf.math.log(probs) # softmax(log(probs)) = probs
log_probs = tf.nn.log_softmax(logits)
label_log_probs = -tf.reduce_sum(log_probs * oh_labels, axis=-1)
numerator = tf.reduce_sum(inputs.masked_lm_weights * label_log_probs)
denominator = tf.reduce_sum(masked_lm_weights) + 1e-6
loss = numerator / denominator
preds = tf.argmax(log_probs, axis=-1, output_type=tf.int32)
MLMOutput = collections.namedtuple(
"MLMOutput", ["logits", "probs", "loss", "per_example_loss", "preds"])
return MLMOutput(
logits=logits, probs=probs, per_example_loss=label_log_probs,
loss=loss, preds=preds)
def _sampling_a_subset(self, logZ, logp, max_predictions_per_seq):
shape = modeling.get_shape_list(logp, expected_rank=2)
seq_len = shape[1]
def gather_z_indexes(sequence_tensor, positions):
"""Gathers the vectors at the specific positions over a minibatch."""
# set negative indices to zeros
mask = tf.zeros_like(positions, dtype=tf.int32)
masked_position = tf.reduce_max(tf.stack([positions, mask]), 0)
index = tf.reshape(
tf.cast(tf.where(tf.equal(mask, 0)), dtype=tf.int32), [-1])
flat_offsets = index * (max_predictions_per_seq + 1)
flat_positions = masked_position + flat_offsets
flat_sequence_tensor = tf.reshape(sequence_tensor, [-1])
output_tensor = tf.gather(flat_sequence_tensor, flat_positions)
return output_tensor
def sampling_loop_cond(j, subset, count, left, log_q):
# j < N and left > 0
# we want to exclude last tokens, because it's always a special token [SEP]
return tf.logical_or(tf.less(j, seq_len),
tf.greater(tf.reduce_sum(left), 0))
def sampling_body(j, subset, count, left, log_q):
# calculate log_q_yes and log_q_no
logp_j = logp[:, j]
log_Z_total = gather_z_indexes(logZ[:, j, :], left) # b
log_Z_yes = gather_z_indexes(logZ[:, j + 1, :], left - 1) # b
logit_yes = logp_j + log_Z_yes - log_Z_total
logit_no = tf.log(
tf.clip_by_value(1 - tf.exp(logit_yes), 1e-20, 1.0))
# draw 2 Gumbel noise and compute action by argmax
logits = tf.transpose(tf.stack([logit_no, logit_yes]), [1, 0])
actions = gumbel.gumbel_softmax(logits)
action_mask = tf.cast(tf.argmax(actions, 1), dtype=tf.int32)
no_left_mask = tf.where(tf.greater(left, 0),
tf.ones_like(left, dtype=tf.int32),
tf.zeros_like(left, dtype=tf.int32))
output = action_mask * no_left_mask
actions = tf.reduce_max(actions, 1)
log_actions = tf.log(actions)
# compute log_q_j and update count and subset
count = count + output
left = left - output
log_q = log_q + log_actions
subset = subset.write(j, output)
return [tf.add(j, 1), subset, count, left, log_q]
with tf.variable_scope("teacher/sampling"):
# Batch sampling
subset = tf.TensorArray(tf.int32, size=seq_len)
count = tf.zeros_like(logp[:, 0], dtype=tf.dtypes.int32)
left = tf.ones_like(logp[:, 0], dtype=tf.dtypes.int32)
left = left * max_predictions_per_seq
log_q = tf.zeros_like(count, dtype=tf.dtypes.float32)
_, subset, count, left, log_q = tf.while_loop(
sampling_loop_cond, sampling_body,
[tf.constant(0), subset, count, left, log_q])
subset = subset.stack() # K x b x N
subset = tf.transpose(subset, [1, 0])
return subset, log_q
def _calculate_partition_table(self, input_mask, action_prob,
max_predictions_per_seq):
shape = modeling.get_shape_list(action_prob, expected_rank=2)
seq_len = shape[1]
with tf.variable_scope("teacher/dp"):
'''
Calculate DP table: aims to calculate logZ[0,K]
# We add an extra row so that when we calculate log_q_yes, we don't have out of bound error
# Z[b,N+1,k] = log 0 - we do not allow to choose anything
# logZ size batch_size x N+1 x K+1
'''
initZ = tf.TensorArray(tf.float32,
size=max_predictions_per_seq + 1)
logZ_0 = tf.zeros_like(input_mask, dtype=tf.float32) # size b x N
logZ_0 = tf.pad(logZ_0, [[0, 0], [0, 1]],
"CONSTANT") # size b x N+1
initZ = initZ.write(tf.constant(0), logZ_0)
# mask logp
action_prob = tf.cast(input_mask, dtype=tf.float32) * action_prob
action_prob = tf.clip_by_value(action_prob, 1e-20, 1.0)
logp = tf.log(action_prob)
logp_no = tf.log(1 - action_prob)
accum_logp = tf.cumsum(logp, axis=1, reverse=True)
def accum_cond(j, logZ_j, logb, loga):
return tf.greater(j, -1)
def accum_body(j, logZ_j, logb, loga):
# logb: log_yes = logp[j] + logZ[j+1, k-1] -- already compute
# loga: log_no = log(1-p[j]) + logZ[j+1, k]
logb_j = tf.squeeze(logb[:, j])
log_one_minus_p_j = tf.squeeze(logp_no[:, j])
loga = loga + log_one_minus_p_j
next_logZ_j = tf.math.reduce_logsumexp(
tf.stack([loga, logb_j]), 0)
logZ_j = logZ_j.write(j, next_logZ_j)
return [tf.subtract(j, 1), logZ_j, logb, next_logZ_j]
def dp_loop_cond(k, logZ, lastZ):
return tf.less(k, max_predictions_per_seq + 1)
def dp_body(k, logZ, lastZ):
'''
case j < N-k + 1:
logZ[j,k] = log_sum( log(1-pi(j)) + logZ[j+1,k], logp(j) + logZ[j+1,k-1])
case j = N-k + 1
logZ[j,k] = accum_logp[j]
case j > N-k + 1
logZ[j,k] = 0
'''
# shift lastZ one step
shifted_lastZ = tf.roll(lastZ[:, :-1], shift=1,
axis=1) #logZ[j+1,k-1]
log_yes = logp + shifted_lastZ # b x N
logZ_j = tf.TensorArray(tf.float32, size=seq_len + 1)
init_value = accum_logp[:, seq_len - k]
logZ_j = logZ_j.write(seq_len - k, init_value)
_, logZ_j, logb, loga = tf.while_loop(
accum_cond, accum_body,
[seq_len - k - 1, logZ_j, log_yes, init_value])
logZ_j = logZ_j.stack() # N x b
logZ_j = tf.transpose(logZ_j, [1, 0]) # b x N
logZ = logZ.write(k, logZ_j)
return [tf.add(k, 1), logZ, logZ_j]
k = tf.constant(1)
_, logZ, lastZ = tf.while_loop(dp_loop_cond,
dp_body, [k, initZ, logZ_0],
shape_invariants=[
k.get_shape(),
tf.TensorShape([]),
tf.TensorShape([None, None])
])
logZ = logZ.stack() # N x b x N
logZ = tf.transpose(logZ, [1, 2, 0])
return logZ, logp
def _get_richer_data(self, fake_data):
inputs_tf = fake_data.inputs.input_ids
labels_tf = fake_data.is_fake_tokens
lens_tf = tf.reduce_sum(fake_data.inputs.input_mask, 1)
#retrieve the basic config
V = self._bert_config.vocab_size
#sub: 10%, del + ins: 5%
N = int(self._config.max_predictions_per_seq * self._config.rich_prob)
B, L = modeling.get_shape_list(inputs_tf)
nlms = 0
bilm = None
if self._config.use_bilm:
with open(self._config.bilm_file, 'rb') as f:
bilm = tf.constant(np.load(f), tf.int32)
_, nlms = modeling.get_shape_list(bilm)
#make multiple partitions for edit op
splits_list = []
for i in range(B):
one = tf.random.uniform([N * 4], 1, lens_tf[i], tf.int32)
one, _ = tf.unique(one)
one = tf.cond(tf.less(tf.shape(one)[0], N * 2 + 1),
lambda: tf.expand_dims(tf.range(1, N * 2 + 2), 0),
lambda: tf.sort(tf.reshape(one[: N * 2 + 1], [1, N * 2 + 1])))
splits_list.append(one[:, 2::2])
splits_tf = tf.concat(splits_list, 0)
splits_up = tf.concat([splits_tf, tf.expand_dims(tf.constant([L] * B, tf.int32), 1)], 1)
splits_lo = tf.concat([tf.expand_dims(tf.constant([0] * B, tf.int32), 1), splits_tf], 1)
size_splits = splits_up - splits_lo
#update the inputs and labels giving random insertion and deletion
new_labels_list = []
new_inputs_list = []
for i in range(B):
inputs_splits = tf.split(inputs_tf[i, :], size_splits[i, :])
labels_splits = tf.split(labels_tf[i, :], size_splits[i, :])
one_inputs = []
one_labels = []
size_split = len(inputs_splits)
inputs_end = inputs_splits[-1]
labels_end = labels_splits[-1]
for j in range(size_split-1):
inputs = inputs_splits[j]
labels = labels_splits[j] #label 1 for substistution
rand_op = random.randint(2, self._config.num_preds - 1)
if rand_op == 2: #label 2 for insertion
if bilm is None: #noise
insert_tok = tf.random.uniform([1], 1, V, tf.int32)
else: #2-gram prediction
insert_tok = tf.expand_dims(bilm[inputs[-1], random.randint(0, nlms-1)], 0)
is_end_valid = tf.less_equal(2, tf.shape(inputs_end)[0])
inputs = tf.cond(is_end_valid, lambda: tf.concat([inputs, insert_tok], 0), lambda: inputs)
labels = tf.cond(is_end_valid, lambda: tf.concat([labels, tf.constant([2])], 0), lambda: labels)
inputs_end = tf.cond(is_end_valid, lambda: inputs_end[:-1], lambda: inputs_end)
labels_end = tf.cond(is_end_valid, lambda: labels_end[:-1], lambda: labels_end)
elif rand_op == 3: #label 3 for deletion
labels = tf.concat([labels[:-2], tf.constant([3])], 0)
inputs = inputs[:-1]
inputs_end = tf.concat([inputs_end, tf.constant([0])], 0)
labels_end = tf.concat([labels_end, tf.constant([0])], 0)
elif rand_op == 4: #label 4 for swapping
labels = tf.concat([labels[:-1], tf.constant([4])], 0)
inputs = tf.concat([inputs[:-2], [inputs[-1]], [inputs[-2]]], 0)
one_labels.append(labels)
one_inputs.append(inputs)
one_inputs.append(inputs_end)
one_labels.append(labels_end)
one_inputs_tf = tf.concat(one_inputs, 0)
one_labels_tf = tf.concat(one_labels, 0)
one_inputs_tf = tf.cond(tf.less(lens_tf[i], N * 2 + 1), lambda: inputs_tf[i, :], lambda: one_inputs_tf)
one_labels_tf = tf.cond(tf.less(lens_tf[i], N * 2 + 1), lambda: labels_tf[i, :], lambda: one_labels_tf)
new_inputs_list.append(tf.expand_dims(one_inputs_tf, 0))
new_labels_list.append(tf.expand_dims(one_labels_tf, 0))
new_inputs_tf = tf.concat(new_inputs_list, 0)
new_labels_tf = tf.concat(new_labels_list, 0)
new_input_mask = tf.cast(tf.not_equal(new_inputs_tf, 0), tf.int32)
updated_inputs = pretrain_data.get_updated_inputs(
fake_data.inputs, input_ids=new_inputs_tf, input_mask=new_input_mask)
RicherData = collections.namedtuple("RicherData", [
"inputs", "is_fake_tokens", "sampled_tokens"])
return RicherData(inputs=updated_inputs, is_fake_tokens=new_labels_tf,
sampled_tokens=fake_data.sampled_tokens)
def __init__(self, config: configure_pretraining.PretrainingConfig,
features, is_training):
# Set up model config
self._config = config
self._bert_config = training_utils.get_bert_config(config)
self._teacher_config = training_utils.get_teacher_config(config)
embedding_size = (self._bert_config.hidden_size
if config.embedding_size is None else
config.embedding_size)
tokenizer = tokenization.FullTokenizer(
config.vocab_file, do_lower_case=config.do_lower_case)
self._vocab = tokenizer.vocab
self._inv_vocab = tokenizer.inv_vocab
# Mask the input
inputs = pretrain_data.features_to_inputs(features)
old_model = self._build_transformer(inputs,
is_training,
embedding_size=embedding_size)
input_states = old_model.get_sequence_output()
input_states = tf.stop_gradient(input_states)
teacher_output = self._build_teacher(input_states,
inputs,
is_training,
embedding_size=embedding_size)
# calculate the proposal distribution
action_prob = teacher_output.action_probs #pi(x_i)
coin_toss = tf.random.uniform([])
log_q, masked_inputs = self._sample_masking_subset(inputs, action_prob)
if config.masking_strategy == pretrain_helpers.MIX_ADV_STRATEGY:
random_masked_input = pretrain_helpers.mask(
config, pretrain_data.features_to_inputs(features),
config.mask_prob)
B, L = modeling.get_shape_list(inputs.input_ids)
N = config.max_predictions_per_seq
strategy_prob = tf.random.uniform([B])
strategy_prob = tf.expand_dims(
tf.cast(tf.greater(strategy_prob, 0.5), tf.int32), 1)
l_strategy_prob = tf.tile(strategy_prob, [1, L])
n_strategy_prob = tf.tile(strategy_prob, [1, N])
mix_input_ids = masked_inputs.input_ids * l_strategy_prob + random_masked_input.input_ids * (
1 - l_strategy_prob)
mix_masked_lm_positions = masked_inputs.masked_lm_positions * n_strategy_prob + random_masked_input.masked_lm_positions * (
1 - n_strategy_prob)
mix_masked_lm_ids = masked_inputs.masked_lm_ids * n_strategy_prob + random_masked_input.masked_lm_ids * (
1 - n_strategy_prob)
n_strategy_prob = tf.cast(n_strategy_prob, tf.float32)
mix_masked_lm_weights = masked_inputs.masked_lm_weights * n_strategy_prob + random_masked_input.masked_lm_weights * (
1 - n_strategy_prob)
mix_masked_inputs = pretrain_data.get_updated_inputs(
inputs,
input_ids=tf.stop_gradient(mix_input_ids),
masked_lm_positions=mix_masked_lm_positions,
masked_lm_ids=mix_masked_lm_ids,
masked_lm_weights=mix_masked_lm_weights,
tag_ids=inputs.tag_ids)
masked_inputs = mix_masked_inputs
# BERT model
model = self._build_transformer(masked_inputs,
is_training,
reuse=tf.AUTO_REUSE,
embedding_size=embedding_size)
mlm_output = self._get_masked_lm_output(masked_inputs, model)
self.total_loss = mlm_output.loss
# Teacher reward is the -log p(x_S|x;B)
reward = tf.stop_gradient(
tf.reduce_mean(mlm_output.per_example_loss, 1))
self._baseline = tf.reduce_mean(reward, -1)
self._std = tf.math.reduce_std(reward, -1)
# Calculate teacher loss
def compute_teacher_loss(log_q, reward, baseline, std):
advantage = tf.abs((reward - baseline) / std)
advantage = tf.stop_gradient(advantage)
log_q = tf.Print(log_q, [log_q], "log_q: ")
teacher_loss = tf.reduce_mean(-log_q * advantage)
return teacher_loss
teacher_loss = tf.cond(
coin_toss < 0.1, lambda: compute_teacher_loss(
log_q, reward, self._baseline, self._std),
lambda: tf.constant(0.0))
self.total_loss = mlm_output.loss + teacher_loss
self.teacher_loss = teacher_loss
self.mlm_loss = mlm_output.loss
# Evaluation`
eval_fn_inputs = {
"input_ids": masked_inputs.input_ids,
"masked_lm_preds": mlm_output.preds,
"mlm_loss": mlm_output.per_example_loss,
"masked_lm_ids": masked_inputs.masked_lm_ids,
"masked_lm_weights": masked_inputs.masked_lm_weights,
"input_mask": masked_inputs.input_mask
}
eval_fn_keys = eval_fn_inputs.keys()
eval_fn_values = [eval_fn_inputs[k] for k in eval_fn_keys]
"""Computes the loss and accuracy of the model."""
d = {k: arg for k, arg in zip(eval_fn_keys, eval_fn_values)}
metrics = dict()
metrics["masked_lm_accuracy"] = tf.metrics.accuracy(
labels=tf.reshape(d["masked_lm_ids"], [-1]),
predictions=tf.reshape(d["masked_lm_preds"], [-1]),
weights=tf.reshape(d["masked_lm_weights"], [-1]))
metrics["masked_lm_loss"] = tf.metrics.mean(
values=tf.reshape(d["mlm_loss"], [-1]),
weights=tf.reshape(d["masked_lm_weights"], [-1]))
self.eval_metrics = metrics
