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ernie.py
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ernie.py
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# Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserved.
#
# 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.
"""Ernie model."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import json
import six
import paddle.fluid as fluid
from model.transformer_encoder import encoder, pre_process_layer
class ErnieConfig(object):
def __init__(self, config_path):
self._config_dict = self._parse(config_path)
def _parse(self, config_path):
try:
with open(config_path) as json_file:
config_dict = json.load(json_file)
except Exception:
raise IOError("Error in parsing Ernie model config file '%s'" %
config_path)
else:
return config_dict
def __getitem__(self, key):
return self._config_dict[key]
def print_config(self):
for arg, value in sorted(six.iteritems(self._config_dict)):
print('%s: %s' % (arg, value))
print('------------------------------------------------')
class ErnieModel(object):
def __init__(self,
src_ids,
position_ids,
sentence_ids,
input_mask,
config,
weight_sharing=True,
use_fp16=False):
self._emb_size = config['hidden_size']
self._n_layer = config['num_hidden_layers']
self._n_head = config['num_attention_heads']
self._voc_size = config['vocab_size']
self._max_position_seq_len = config['max_position_embeddings']
self._sent_types = config['type_vocab_size']
self._hidden_act = config['hidden_act']
self._prepostprocess_dropout = config['hidden_dropout_prob']
self._attention_dropout = config['attention_probs_dropout_prob']
self._weight_sharing = weight_sharing
self._word_emb_name = "word_embedding"
self._pos_emb_name = "pos_embedding"
self._sent_emb_name = "sent_embedding"
self._dtype = "float16" if use_fp16 else "float32"
# Initialize all weigths by truncated normal initializer, and all biases
# will be initialized by constant zero by default.
self._param_initializer = fluid.initializer.TruncatedNormal(
scale=config['initializer_range'])
self._build_model(src_ids, position_ids, sentence_ids, input_mask)
def _build_model(self, src_ids, position_ids, sentence_ids, input_mask):
# padding id in vocabulary must be set to 0
emb_out = fluid.layers.embedding(
input=src_ids,
size=[self._voc_size, self._emb_size],
dtype=self._dtype,
param_attr=fluid.ParamAttr(
name=self._word_emb_name, initializer=self._param_initializer),
is_sparse=False)
position_emb_out = fluid.layers.embedding(
input=position_ids,
size=[self._max_position_seq_len, self._emb_size],
dtype=self._dtype,
param_attr=fluid.ParamAttr(
name=self._pos_emb_name, initializer=self._param_initializer))
sent_emb_out = fluid.layers.embedding(
sentence_ids,
size=[self._sent_types, self._emb_size],
dtype=self._dtype,
param_attr=fluid.ParamAttr(
name=self._sent_emb_name, initializer=self._param_initializer))
emb_out = emb_out + position_emb_out
emb_out = emb_out + sent_emb_out
emb_out = pre_process_layer(
emb_out, 'nd', self._prepostprocess_dropout, name='pre_encoder')
if self._dtype == "float16":
input_mask = fluid.layers.cast(x=input_mask, dtype=self._dtype)
self_attn_mask = fluid.layers.matmul(
x=input_mask, y=input_mask, transpose_y=True)
self_attn_mask = fluid.layers.scale(
x=self_attn_mask, scale=10000.0, bias=-1.0, bias_after_scale=False)
n_head_self_attn_mask = fluid.layers.stack(
x=[self_attn_mask] * self._n_head, axis=1)
n_head_self_attn_mask.stop_gradient = True
self._enc_out = encoder(
enc_input=emb_out,
attn_bias=n_head_self_attn_mask,
n_layer=self._n_layer,
n_head=self._n_head,
d_key=self._emb_size // self._n_head,
d_value=self._emb_size // self._n_head,
d_model=self._emb_size,
d_inner_hid=self._emb_size * 4,
prepostprocess_dropout=self._prepostprocess_dropout,
attention_dropout=self._attention_dropout,
relu_dropout=0,
hidden_act=self._hidden_act,
preprocess_cmd="",
postprocess_cmd="dan",
param_initializer=self._param_initializer,
name='encoder')
def get_sequence_output(self):
return self._enc_out
def get_pooled_output(self):
"""Get the first feature of each sequence for classification"""
next_sent_feat = fluid.layers.slice(
input=self._enc_out, axes=[1], starts=[0], ends=[1])
next_sent_feat = fluid.layers.fc(
input=next_sent_feat,
size=self._emb_size,
act="tanh",
param_attr=fluid.ParamAttr(
name="pooled_fc.w_0", initializer=self._param_initializer),
bias_attr="pooled_fc.b_0")
return next_sent_feat
def get_pretraining_output(self, mask_label, mask_pos, labels):
"""Get the loss & accuracy for pretraining"""
mask_pos = fluid.layers.cast(x=mask_pos, dtype='int32')
# extract the first token feature in each sentence
next_sent_feat = self.get_pooled_output()
reshaped_emb_out = fluid.layers.reshape(
x=self._enc_out, shape=[-1, self._emb_size])
# extract masked tokens' feature
mask_feat = fluid.layers.gather(input=reshaped_emb_out, index=mask_pos)
# transform: fc
mask_trans_feat = fluid.layers.fc(
input=mask_feat,
size=self._emb_size,
act=self._hidden_act,
param_attr=fluid.ParamAttr(
name='mask_lm_trans_fc.w_0',
initializer=self._param_initializer),
bias_attr=fluid.ParamAttr(name='mask_lm_trans_fc.b_0'))
# transform: layer norm
mask_trans_feat = pre_process_layer(
mask_trans_feat, 'n', name='mask_lm_trans')
mask_lm_out_bias_attr = fluid.ParamAttr(
name="mask_lm_out_fc.b_0",
initializer=fluid.initializer.Constant(value=0.0))
if self._weight_sharing:
fc_out = fluid.layers.matmul(
x=mask_trans_feat,
y=fluid.default_main_program().global_block().var(
self._word_emb_name),
transpose_y=True)
fc_out += fluid.layers.create_parameter(
shape=[self._voc_size],
dtype=self._dtype,
attr=mask_lm_out_bias_attr,
is_bias=True)
else:
fc_out = fluid.layers.fc(input=mask_trans_feat,
size=self._voc_size,
param_attr=fluid.ParamAttr(
name="mask_lm_out_fc.w_0",
initializer=self._param_initializer),
bias_attr=mask_lm_out_bias_attr)
mask_lm_loss = fluid.layers.softmax_with_cross_entropy(
logits=fc_out, label=mask_label)
mean_mask_lm_loss = fluid.layers.mean(mask_lm_loss)
next_sent_fc_out = fluid.layers.fc(
input=next_sent_feat,
size=2,
param_attr=fluid.ParamAttr(
name="next_sent_fc.w_0", initializer=self._param_initializer),
bias_attr="next_sent_fc.b_0")
next_sent_loss, next_sent_softmax = fluid.layers.softmax_with_cross_entropy(
logits=next_sent_fc_out, label=labels, return_softmax=True)
next_sent_acc = fluid.layers.accuracy(
input=next_sent_softmax, label=labels)
mean_next_sent_loss = fluid.layers.mean(next_sent_loss)
loss = mean_next_sent_loss + mean_mask_lm_loss
return next_sent_acc, mean_mask_lm_loss, loss