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convert_fair_to_pt.py
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convert_fair_to_pt.py
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# coding=utf-8
# Copyright 2018 The HuggingFace Inc. team.
#
# 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.
"""Convert RoBERTa checkpoint."""
import argparse
import pathlib
import fairseq
import torch
from fairseq.models.roberta import RobertaModel as FairseqRobertaModel
from fairseq.modules import TransformerSentenceEncoderLayer
from packaging import version
from transformers import RobertaConfig, RobertaForMaskedLM, RobertaForSequenceClassification
from transformers.models.bert.modeling_bert import (
BertIntermediate,
BertLayer,
BertOutput,
BertSelfAttention,
BertSelfOutput,
)
from transformers.utils import logging
if version.parse(fairseq.__version__) < version.parse("0.9.0"):
raise Exception("requires fairseq >= 0.9.0")
logging.set_verbosity_info()
logger = logging.get_logger(__name__)
SAMPLE_TEXT = "Hello world! cécé herlolip"
def convert_roberta_checkpoint_to_pytorch(
roberta_checkpoint_path: str, pytorch_dump_folder_path: str, classification_head: bool
):
"""
Copy/paste/tweak roberta's weights to our BERT structure.
"""
roberta = FairseqRobertaModel.from_pretrained(roberta_checkpoint_path)
roberta.eval() # disable dropout
roberta_sent_encoder = roberta.model.encoder.sentence_encoder
config = RobertaConfig(
vocab_size=roberta_sent_encoder.embed_tokens.num_embeddings,
hidden_size=roberta.model.encoder.args.encoder_embed_dim,
num_hidden_layers=roberta.model.encoder.args.encoder_layers,
num_attention_heads=roberta.model.encoder.args.encoder_attention_heads,
intermediate_size=roberta.model.encoder.args.encoder_ffn_embed_dim,
max_position_embeddings=514,
type_vocab_size=1,
layer_norm_eps=1e-5, # PyTorch default used in fairseq
)
if classification_head:
config.num_labels = roberta.model.classification_heads["mnli"].out_proj.weight.shape[0]
print("Our BERT config:", config)
model = RobertaForSequenceClassification(config) if classification_head else RobertaForMaskedLM(config)
model.eval()
# Now let's copy all the weights.
# Embeddings
model.roberta.embeddings.word_embeddings.weight = roberta_sent_encoder.embed_tokens.weight
model.roberta.embeddings.position_embeddings.weight = roberta_sent_encoder.embed_positions.weight
model.roberta.embeddings.token_type_embeddings.weight.data = torch.zeros_like(
model.roberta.embeddings.token_type_embeddings.weight
) # just zero them out b/c RoBERTa doesn't use them.
model.roberta.embeddings.LayerNorm.weight = roberta_sent_encoder.layernorm_embedding.weight
model.roberta.embeddings.LayerNorm.bias = roberta_sent_encoder.layernorm_embedding.bias
for i in range(config.num_hidden_layers):
# Encoder: start of layer
layer: BertLayer = model.roberta.encoder.layer[i]
roberta_layer: TransformerSentenceEncoderLayer = roberta_sent_encoder.layers[i]
# self attention
self_attn: BertSelfAttention = layer.attention.self
assert (
roberta_layer.self_attn.k_proj.weight.data.shape
== roberta_layer.self_attn.q_proj.weight.data.shape
== roberta_layer.self_attn.v_proj.weight.data.shape
== torch.Size((config.hidden_size, config.hidden_size))
)
self_attn.query.weight.data = roberta_layer.self_attn.q_proj.weight
self_attn.query.bias.data = roberta_layer.self_attn.q_proj.bias
self_attn.key.weight.data = roberta_layer.self_attn.k_proj.weight
self_attn.key.bias.data = roberta_layer.self_attn.k_proj.bias
self_attn.value.weight.data = roberta_layer.self_attn.v_proj.weight
self_attn.value.bias.data = roberta_layer.self_attn.v_proj.bias
# self-attention output
self_output: BertSelfOutput = layer.attention.output
assert self_output.dense.weight.shape == roberta_layer.self_attn.out_proj.weight.shape
self_output.dense.weight = roberta_layer.self_attn.out_proj.weight
self_output.dense.bias = roberta_layer.self_attn.out_proj.bias
self_output.LayerNorm.weight = roberta_layer.self_attn_layer_norm.weight
self_output.LayerNorm.bias = roberta_layer.self_attn_layer_norm.bias
# intermediate
intermediate: BertIntermediate = layer.intermediate
assert intermediate.dense.weight.shape == roberta_layer.fc1.weight.shape
intermediate.dense.weight = roberta_layer.fc1.weight
intermediate.dense.bias = roberta_layer.fc1.bias
# output
bert_output: BertOutput = layer.output
assert bert_output.dense.weight.shape == roberta_layer.fc2.weight.shape
bert_output.dense.weight = roberta_layer.fc2.weight
bert_output.dense.bias = roberta_layer.fc2.bias
bert_output.LayerNorm.weight = roberta_layer.final_layer_norm.weight
bert_output.LayerNorm.bias = roberta_layer.final_layer_norm.bias
# end of layer
if classification_head:
model.classifier.dense.weight = roberta.model.classification_heads["mnli"].dense.weight
model.classifier.dense.bias = roberta.model.classification_heads["mnli"].dense.bias
model.classifier.out_proj.weight = roberta.model.classification_heads["mnli"].out_proj.weight
model.classifier.out_proj.bias = roberta.model.classification_heads["mnli"].out_proj.bias
else:
# LM Head
model.lm_head.dense.weight = roberta.model.encoder.lm_head.dense.weight
model.lm_head.dense.bias = roberta.model.encoder.lm_head.dense.bias
model.lm_head.layer_norm.weight = roberta.model.encoder.lm_head.layer_norm.weight
model.lm_head.layer_norm.bias = roberta.model.encoder.lm_head.layer_norm.bias
model.lm_head.decoder.weight = roberta.model.encoder.lm_head.weight
model.lm_head.decoder.bias = roberta.model.encoder.lm_head.bias
# Let's check that we get the same results.
input_ids: torch.Tensor = roberta.encode(SAMPLE_TEXT).unsqueeze(0) # batch of size 1
our_output = model(input_ids)[0]
if classification_head:
their_output = roberta.model.classification_heads["mnli"](roberta.extract_features(input_ids))
else:
their_output = roberta.model(input_ids)[0]
print(our_output.shape, their_output.shape)
max_absolute_diff = torch.max(torch.abs(our_output - their_output)).item()
print(f"max_absolute_diff = {max_absolute_diff}") # ~ 1e-7
success = torch.allclose(our_output, their_output, atol=1e-3)
print("Do both models output the same tensors?", "🔥" if success else "💩")
if not success:
raise Exception("Something went wRoNg")
pathlib.Path(pytorch_dump_folder_path).mkdir(parents=True, exist_ok=True)
print(f"Saving model to {pytorch_dump_folder_path}")
model.save_pretrained(pytorch_dump_folder_path)
if __name__ == "__main__":
parser = argparse.ArgumentParser()
# Required parameters
parser.add_argument(
"--roberta_checkpoint_path", default=None, type=str, required=True, help="Path the official PyTorch dump."
)
parser.add_argument(
"--pytorch_dump_folder_path", default=None, type=str, required=True, help="Path to the output PyTorch model."
)
parser.add_argument(
"--classification_head", action="store_true", help="Whether to convert a final classification head."
)
args = parser.parse_args()
convert_roberta_checkpoint_to_pytorch(
args.roberta_checkpoint_path, args.pytorch_dump_folder_path, args.classification_head
)