official/projects/mobilebert/model_utils.py
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"""Checkpoint converter for Mobilebert."""
import copy
import json
import tensorflow.compat.v1 as tf
from official.modeling import tf_utils
from official.nlp.modeling import layers
from official.nlp.modeling import models
from official.nlp.modeling import networks
class BertConfig(object):
"""Configuration for `BertModel`."""
def __init__(self,
vocab_size,
hidden_size=768,
num_hidden_layers=12,
num_attention_heads=12,
intermediate_size=3072,
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,
embedding_size=None,
trigram_input=False,
use_bottleneck=False,
intra_bottleneck_size=None,
use_bottleneck_attention=False,
key_query_shared_bottleneck=False,
num_feedforward_networks=1,
normalization_type="layer_norm",
classifier_activation=True):
"""Constructs BertConfig.
Args:
vocab_size: Vocabulary size of `inputs_ids` in `BertModel`.
hidden_size: Size of the encoder layers and the pooler layer.
num_hidden_layers: Number of hidden layers in the Transformer encoder.
num_attention_heads: Number of attention heads for each attention layer in
the Transformer encoder.
intermediate_size: The size of the "intermediate" (i.e., feed-forward)
layer in the Transformer encoder.
hidden_act: The non-linear activation function (function or string) in the
encoder and pooler.
hidden_dropout_prob: The dropout probability for all fully connected
layers in the embeddings, encoder, and pooler.
attention_probs_dropout_prob: The dropout ratio for the attention
probabilities.
max_position_embeddings: The maximum sequence length that this model might
ever be used with. Typically set this to something large just in case
(e.g., 512 or 1024 or 2048).
type_vocab_size: The vocabulary size of the `token_type_ids` passed into
`BertModel`.
initializer_range: The stdev of the truncated_normal_initializer for
initializing all weight matrices.
embedding_size: The size of the token embedding.
trigram_input: Use a convolution of trigram as input.
use_bottleneck: Use the bottleneck/inverted-bottleneck structure in BERT.
intra_bottleneck_size: The hidden size in the bottleneck.
use_bottleneck_attention: Use attention inputs from the bottleneck
transformation.
key_query_shared_bottleneck: Use the same linear transformation for
query&key in the bottleneck.
num_feedforward_networks: Number of FFNs in a block.
normalization_type: The normalization type in BERT.
classifier_activation: Using the tanh activation for the final
representation of the [CLS] token in fine-tuning.
"""
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.hidden_act = hidden_act
self.intermediate_size = intermediate_size
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.embedding_size = embedding_size
self.trigram_input = trigram_input
self.use_bottleneck = use_bottleneck
self.intra_bottleneck_size = intra_bottleneck_size
self.use_bottleneck_attention = use_bottleneck_attention
self.key_query_shared_bottleneck = key_query_shared_bottleneck
self.num_feedforward_networks = num_feedforward_networks
self.normalization_type = normalization_type
self.classifier_activation = classifier_activation
@classmethod
def from_dict(cls, json_object):
"""Constructs a `BertConfig` from a Python dictionary of parameters."""
config = BertConfig(vocab_size=None)
for (key, value) in json_object.items():
config.__dict__[key] = value
if config.embedding_size is None:
config.embedding_size = config.hidden_size
if config.intra_bottleneck_size is None:
config.intra_bottleneck_size = config.hidden_size
return config
@classmethod
def from_json_file(cls, json_file):
"""Constructs a `BertConfig` from a json file of parameters."""
with tf.gfile.GFile(json_file, "r") as reader:
text = reader.read()
return cls.from_dict(json.loads(text))
def to_dict(self):
"""Serializes this instance to a Python dictionary."""
output = copy.deepcopy(self.__dict__)
return output
def to_json_string(self):
"""Serializes this instance to a JSON string."""
return json.dumps(self.to_dict(), indent=2, sort_keys=True) + "\n"
def create_mobilebert_pretrainer(bert_config):
"""Creates a BertPretrainerV2 that wraps MobileBERTEncoder model."""
mobilebert_encoder = networks.MobileBERTEncoder(
word_vocab_size=bert_config.vocab_size,
word_embed_size=bert_config.embedding_size,
type_vocab_size=bert_config.type_vocab_size,
max_sequence_length=bert_config.max_position_embeddings,
num_blocks=bert_config.num_hidden_layers,
hidden_size=bert_config.hidden_size,
num_attention_heads=bert_config.num_attention_heads,
intermediate_size=bert_config.intermediate_size,
intermediate_act_fn=tf_utils.get_activation(bert_config.hidden_act),
hidden_dropout_prob=bert_config.hidden_dropout_prob,
attention_probs_dropout_prob=bert_config.attention_probs_dropout_prob,
intra_bottleneck_size=bert_config.intra_bottleneck_size,
initializer_range=bert_config.initializer_range,
use_bottleneck_attention=bert_config.use_bottleneck_attention,
key_query_shared_bottleneck=bert_config.key_query_shared_bottleneck,
num_feedforward_networks=bert_config.num_feedforward_networks,
normalization_type=bert_config.normalization_type,
classifier_activation=bert_config.classifier_activation)
masked_lm = layers.MobileBertMaskedLM(
embedding_table=mobilebert_encoder.get_embedding_table(),
activation=tf_utils.get_activation(bert_config.hidden_act),
initializer=tf_keras.initializers.TruncatedNormal(
stddev=bert_config.initializer_range),
name="cls/predictions")
pretrainer = models.BertPretrainerV2(
encoder_network=mobilebert_encoder, customized_masked_lm=masked_lm)
# Makes sure the pretrainer variables are created.
_ = pretrainer(pretrainer.inputs)
return pretrainer