converter: add conversion script for original XLM-RoBERTa weights to...

converter: add conversion script for original XLM-RoBERTa weights to Transformers-compatible weights

transformers/convert_xlm_roberta_original_pytorch_checkpoint_to_pytorch.py

+# 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."""
+
+from __future__ import absolute_import, division, print_function
+
+import argparse
+import logging
+import numpy as np
+import torch
+import pathlib
+
+from fairseq.models.roberta import RobertaModel as FairseqRobertaModel
+from fairseq.modules import TransformerSentenceEncoderLayer
+from transformers.modeling_bert import (BertConfig, BertEncoder,
+                                        BertIntermediate, BertLayer,
+                                        BertModel, BertOutput,
+                                        BertSelfAttention,
+                                        BertSelfOutput)
+from transformers.modeling_roberta import (RobertaEmbeddings,
+                                           RobertaForMaskedLM,
+                                           RobertaForSequenceClassification,
+                                           RobertaModel)
+
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)
+
+SAMPLE_TEXT = 'Hello world! cécé herlolip'
+
+
+def convert_roberta_checkpoint_to_pytorch(roberta_checkpoint_path, pytorch_dump_folder_path, classification_head):
+    """
+    Copy/paste/tweak roberta's weights to our BERT structure.
+    """
+    roberta = FairseqRobertaModel.from_pretrained(roberta_checkpoint_path, bpe = 'sentencepiece')
+    roberta.eval()  # disable dropout
+    config = BertConfig(
+        vocab_size_or_config_json_file=250004,
+        hidden_size=roberta.args.encoder_embed_dim,
+        num_hidden_layers=roberta.args.encoder_layers,
+        num_attention_heads=roberta.args.encoder_attention_heads,
+        intermediate_size=roberta.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.args.num_classes
+    print("Our BERT config:", config)
+
+    model = RobertaForSequenceClassification(config) if classification_head else RobertaForMaskedLM(config)
+    model.eval()
+
+    # Now let's copy all the weights.
+    # Embeddings
+    roberta_sent_encoder = roberta.model.decoder.sentence_encoder
+    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.emb_layer_norm.weight
+    model.roberta.embeddings.LayerNorm.bias = roberta_sent_encoder.emb_layer_norm.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.decoder.lm_head.dense.weight
+        model.lm_head.dense.bias = roberta.model.decoder.lm_head.dense.bias
+        model.lm_head.layer_norm.weight = roberta.model.decoder.lm_head.layer_norm.weight
+        model.lm_head.layer_norm.bias = roberta.model.decoder.lm_head.layer_norm.bias
+        model.lm_head.decoder.weight = roberta.model.decoder.lm_head.weight
+        model.lm_head.bias = roberta.model.decoder.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
+    )