RoBERTa token classification

[WIP] copy paste bert token classification for roberta

transformers/__init__.py

@@ -89,6 +89,7 @@ if is_torch_available():
                             XLM_PRETRAINED_MODEL_ARCHIVE_MAP)
     from .modeling_roberta import (RobertaForMaskedLM, RobertaModel,
                                 RobertaForSequenceClassification, RobertaForMultipleChoice,
+                                RobertaForTokenClassification,
                                 ROBERTA_PRETRAINED_MODEL_ARCHIVE_MAP)
     from .modeling_distilbert import (DistilBertForMaskedLM, DistilBertModel,
                                 DistilBertForSequenceClassification, DistilBertForQuestionAnswering,
@@ -139,6 +140,7 @@ if is_tf_available():
     from .modeling_tf_roberta import (TFRobertaPreTrainedModel, TFRobertaMainLayer,
                                       TFRobertaModel, TFRobertaForMaskedLM,
                                       TFRobertaForSequenceClassification,
+                                      TFRobertaForTokenClassification,
                                       TF_ROBERTA_PRETRAINED_MODEL_ARCHIVE_MAP)
 
     from .modeling_tf_distilbert import (TFDistilBertPreTrainedModel, TFDistilBertMainLayer,

transformers/modeling_roberta.py

@@ -343,6 +343,7 @@ class RobertaForSequenceClassification(BertPreTrainedModel):
 
         return outputs  # (loss), logits, (hidden_states), (attentions)
 
+
 @add_start_docstrings("""Roberta Model with a multiple choice classification head on top (a linear layer on top of
     the pooled output and a softmax) e.g. for RocStories/SWAG tasks. """,
     ROBERTA_START_DOCSTRING, ROBERTA_INPUTS_DOCSTRING)
@@ -451,6 +452,77 @@ class RobertaForMultipleChoice(BertPreTrainedModel):
         return outputs  # (loss), reshaped_logits, (hidden_states), (attentions)
 
 
+@add_start_docstrings("""Roberta Model with a token classification head on top (a linear layer on top of
+    the hidden-states output) e.g. for Named-Entity-Recognition (NER) tasks. """,
+    ROBERTA_START_DOCSTRING, ROBERTA_INPUTS_DOCSTRING)
+class RobertaForTokenClassification(BertPreTrainedModel):
+    r"""
+        **labels**: (`optional`) ``torch.LongTensor`` of shape ``(batch_size, sequence_length)``:
+            Labels for computing the token classification loss.
+            Indices should be in ``[0, ..., config.num_labels - 1]``.
+
+    Outputs: `Tuple` comprising various elements depending on the configuration (config) and inputs:
+        **loss**: (`optional`, returned when ``labels`` is provided) ``torch.FloatTensor`` of shape ``(1,)``:
+            Classification loss.
+        **scores**: ``torch.FloatTensor`` of shape ``(batch_size, sequence_length, config.num_labels)``
+            Classification scores (before SoftMax).
+        **hidden_states**: (`optional`, returned when ``config.output_hidden_states=True``)
+            list of ``torch.FloatTensor`` (one for the output of each layer + the output of the embeddings)
+            of shape ``(batch_size, sequence_length, hidden_size)``:
+            Hidden-states of the model at the output of each layer plus the initial embedding outputs.
+        **attentions**: (`optional`, returned when ``config.output_attentions=True``)
+            list of ``torch.FloatTensor`` (one for each layer) of shape ``(batch_size, num_heads, sequence_length, sequence_length)``:
+            Attentions weights after the attention softmax, used to compute the weighted average in the self-attention heads.
+
+    Examples::
+
+        tokenizer = RobertaTokenizer.from_pretrained('roberta-base')
+        model = RobertaForTokenClassification.from_pretrained('roberta-base')
+        input_ids = torch.tensor(tokenizer.encode("Hello, my dog is cute")).unsqueeze(0)  # Batch size 1
+        labels = torch.tensor([1] * input_ids.size(1)).unsqueeze(0)  # Batch size 1
+        outputs = model(input_ids, labels=labels)
+        loss, scores = outputs[:2]
+
+    """
+    def __init__(self, config):
+        super(RobertaForTokenClassification, self).__init__(config)
+        self.num_labels = config.num_labels
+
+        self.roberta = RobertaModel(config)
+        self.dropout = nn.Dropout(config.hidden_dropout_prob)
+        self.classifier = nn.Linear(config.hidden_size, config.num_labels)
+
+        self.init_weights()
+
+    def forward(self, input_ids, attention_mask=None, token_type_ids=None,
+                position_ids=None, head_mask=None, labels=None):
+
+        outputs = self.roberta(input_ids,
+                               attention_mask=attention_mask,
+                               token_type_ids=token_type_ids,
+                               position_ids=position_ids,
+                               head_mask=head_mask)
+
+        sequence_output = outputs[0]
+
+        sequence_output = self.dropout(sequence_output)
+        logits = self.classifier(sequence_output)
+
+        outputs = (logits,) + outputs[2:]  # add hidden states and attention if they are here
+        if labels is not None:
+            loss_fct = CrossEntropyLoss()
+            # Only keep active parts of the loss
+            if attention_mask is not None:
+                active_loss = attention_mask.view(-1) == 1
+                active_logits = logits.view(-1, self.num_labels)[active_loss]
+                active_labels = labels.view(-1)[active_loss]
+                loss = loss_fct(active_logits, active_labels)
+            else:
+                loss = loss_fct(logits.view(-1, self.num_labels), labels.view(-1))
+            outputs = (loss,) + outputs
+
+        return outputs  # (loss), scores, (hidden_states), (attentions)
+
 
 class RobertaClassificationHead(nn.Module):
     """Head for sentence-level classification tasks."""

transformers/modeling_tf_roberta.py

@@ -371,3 +371,54 @@ class TFRobertaForSequenceClassification(TFRobertaPreTrainedModel):
         outputs = (logits,) + outputs[2:]
 
         return outputs  # logits, (hidden_states), (attentions)
+
+
+@add_start_docstrings("""RoBERTa Model with a token classification head on top (a linear layer on top of
+    the hidden-states output) e.g. for Named-Entity-Recognition (NER) tasks. """,
+    ROBERTA_START_DOCSTRING, ROBERTA_INPUTS_DOCSTRING)
+class TFRobertaForTokenClassification(TFRobertaPreTrainedModel):
+    r"""
+    Outputs: `Tuple` comprising various elements depending on the configuration (config) and inputs:
+        **scores**: ``Numpy array`` or ``tf.Tensor`` of shape ``(batch_size, sequence_length, config.num_labels)``
+            Classification scores (before SoftMax).
+        **hidden_states**: (`optional`, returned when ``config.output_hidden_states=True``)
+            list of ``Numpy array`` or ``tf.Tensor`` (one for the output of each layer + the output of the embeddings)
+            of shape ``(batch_size, sequence_length, hidden_size)``:
+            Hidden-states of the model at the output of each layer plus the initial embedding outputs.
+        **attentions**: (`optional`, returned when ``config.output_attentions=True``)
+            list of ``Numpy array`` or ``tf.Tensor`` (one for each layer) of shape ``(batch_size, num_heads, sequence_length, sequence_length)``:
+            Attentions weights after the attention softmax, used to compute the weighted average in the self-attention heads.
+
+    Examples::
+
+        import tensorflow as tf
+        from transformers import RobertaTokenizer, TFRobertaForTokenClassification
+
+        tokenizer = RobertaTokenizer.from_pretrained('roberta-base')
+        model = TFRobertaForTokenClassification.from_pretrained('roberta-base')
+        input_ids = tf.constant(tokenizer.encode("Hello, my dog is cute"))[None, :]  # Batch size 1
+        outputs = model(input_ids)
+        scores = outputs[0]
+
+    """
+    def __init__(self, config, *inputs, **kwargs):
+        super(TFRobertaForTokenClassification, self).__init__(config, *inputs, **kwargs)
+        self.num_labels = config.num_labels
+
+        self.roberta = TFRobertaMainLayer(config, name='roberta')
+        self.dropout = tf.keras.layers.Dropout(config.hidden_dropout_prob)
+        self.classifier = tf.keras.layers.Dense(config.num_labels,
+                                                kernel_initializer=get_initializer(config.initializer_range),
+                                                name='classifier')
+
+    def call(self, inputs, **kwargs):
+        outputs = self.roberta(inputs, **kwargs)
+
+        sequence_output = outputs[0]
+
+        sequence_output = self.dropout(sequence_output, training=kwargs.get('training', False))
+        logits = self.classifier(sequence_output)
+
+        outputs = (logits,) + outputs[2:]  # add hidden states and attention if they are here
+
+        return outputs  # scores, (hidden_states), (attentions)

transformers/tests/modeling_roberta_test.py

@@ -24,7 +24,8 @@ from transformers import is_torch_available
 
 if is_torch_available():
     import torch
-    from transformers import (RobertaConfig, RobertaModel, RobertaForMaskedLM, RobertaForSequenceClassification)
+    from transformers import (RobertaConfig, RobertaModel, RobertaForMaskedLM,
+                              RobertaForSequenceClassification, RobertaForTokenClassification)
     from transformers.modeling_roberta import ROBERTA_PRETRAINED_MODEL_ARCHIVE_MAP
 else:
     pytestmark = pytest.mark.skip("Require Torch")
@@ -156,6 +157,22 @@ class RobertaModelTest(CommonTestCases.CommonModelTester):
                 [self.batch_size, self.seq_length, self.vocab_size])
             self.check_loss_output(result)
 
+        def create_and_check_roberta_for_token_classification(self, config, input_ids, token_type_ids, input_mask,
+                                                              sequence_labels, token_labels, choice_labels):
+            config.num_labels = self.num_labels
+            model = RobertaForTokenClassification(config=config)
+            model.eval()
+            loss, logits = model(input_ids, attention_mask=input_mask, token_type_ids=token_type_ids,
+                                 labels=token_labels)
+            result = {
+                "loss": loss,
+                "logits": logits,
+            }
+            self.parent.assertListEqual(
+                list(result["logits"].size()),
+                [self.batch_size, self.seq_length, self.num_labels])
+            self.check_loss_output(result)
+
         def prepare_config_and_inputs_for_common(self):
             config_and_inputs = self.prepare_config_and_inputs()
             (config, input_ids, token_type_ids, input_mask,

transformers/tests/modeling_tf_roberta_test.py

@@ -30,6 +30,7 @@ if is_tf_available():
     import numpy
     from transformers.modeling_tf_roberta import (TFRobertaModel, TFRobertaForMaskedLM,
                                                           TFRobertaForSequenceClassification,
+                                                          TFRobertaForTokenClassification,
                                                           TF_ROBERTA_PRETRAINED_MODEL_ARCHIVE_MAP)
 else:
     pytestmark = pytest.mark.skip("Require TensorFlow")
@@ -154,6 +155,20 @@ class TFRobertaModelTest(TFCommonTestCases.TFCommonModelTester):
                 list(result["prediction_scores"].shape),
                 [self.batch_size, self.seq_length, self.vocab_size])
 
+        def create_and_check_roberta_for_token_classification(self, config, input_ids, token_type_ids, input_mask, sequence_labels, token_labels, choice_labels):
+            config.num_labels = self.num_labels
+            model = TFRobertaForTokenClassification(config=config)
+            inputs = {'input_ids': input_ids,
+                      'attention_mask': input_mask,
+                      'token_type_ids': token_type_ids}
+            logits, = model(inputs)
+            result = {
+                "logits": logits.numpy(),
+            }
+            self.parent.assertListEqual(
+                list(result["logits"].shape),
+                [self.batch_size, self.seq_length, self.num_labels])
+
         def prepare_config_and_inputs_for_common(self):
             config_and_inputs = self.prepare_config_and_inputs()
             (config, input_ids, token_type_ids, input_mask,