Merge pull request #1004 from erenup/master

Refactoring old run_swag.py

examples/README.md

@@ -8,7 +8,8 @@ similar API between the different models.
 | [Language Model fine-tuning](#language-model-fine-tuning) | Fine-tuning the library models for language modeling on a text dataset. Causal language modeling for GPT/GPT-2, masked language modeling for BERT/RoBERTa. |
 | [Language Generation](#language-generation) | Conditional text generation using the auto-regressive models of the library: GPT, GPT-2, Transformer-XL and XLNet.                                         |
 | [GLUE](#glue) | Examples running BERT/XLM/XLNet/RoBERTa on the 9 GLUE tasks. Examples feature distributed training as well as half-precision.                              |
-| [SQuAD](#squad) | Using BERT for question answering, examples with distributed training.                                                                                     |
+| [SQuAD](#squad) | Using BERT for question answering, examples with distributed training.                                                                                  |
+| [Multiple Choice](#multiple choice) | Examples running BERT/XLNet/RoBERTa on the SWAG/RACE/ARC tasks. 
 
 ## Language model fine-tuning
 
@@ -282,6 +283,40 @@ The results  are the following:
   loss = 0.04755385363816904
 ```
 
+##Multiple Choice
+
+Based on the script [`run_multiple_choice.py`]().
+
+#### Fine-tuning on SWAG
+Download [swag](https://github.com/rowanz/swagaf/tree/master/data) data
+
+```
+#training on 4 tesla V100(16GB) GPUS
+export SWAG_DIR=/path/to/swag_data_dir
+python ./examples/single_model_scripts/run_multiple_choice.py \
+--model_type roberta \
+--task_name swag \
+--model_name_or_path roberta-base \
+--do_train \
+--do_eval \
+--do_lower_case \
+--data_dir $SWAG_DIR \
+--learning_rate 5e-5 \
+--num_train_epochs 3 \
+--max_seq_length 80 \
+--output_dir models_bert/swag_base \
+--per_gpu_eval_batch_size=16 \
+--per_gpu_train_batch_size=16 \
+--gradient_accumulation_steps 2 \
+--overwrite_output
+```
+Training with the defined hyper-parameters yields the following results:
+```
+***** Eval results *****
+eval_acc = 0.8338998300509847
+eval_loss = 0.44457291918821606
+```
+
 ## SQuAD
 
 Based on the script [`run_squad.py`](https://github.com/huggingface/pytorch-transformers/blob/master/examples/run_squad.py).

examples/utils_multiple_choice.py

+# coding=utf-8
+# Copyright 2018 The Google AI Language Team Authors and The HuggingFace Inc. team.
+# Copyright (c) 2018, NVIDIA CORPORATION.  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.
+""" BERT multiple choice fine-tuning: utilities to work with multiple choice tasks of reading comprehension  """
+
+from __future__ import absolute_import, division, print_function
+
+
+import logging
+import os
+import sys
+from io import open
+import json
+import csv
+import glob
+import tqdm
+
+
+logger = logging.getLogger(__name__)
+
+
+class InputExample(object):
+    """A single training/test example for multiple choice"""
+
+    def __init__(self, example_id, question,  contexts, endings, label=None):
+        """Constructs a InputExample.
+
+        Args:
+            example_id: Unique id for the example.
+            contexts: list of str. The untokenized text of the first sequence (context of corresponding question).
+            question: string. The untokenized text of the second sequence (qustion).
+            endings: list of str. multiple choice's options. Its length must be equal to contexts' length.
+            label: (Optional) string. The label of the example. This should be
+            specified for train and dev examples, but not for test examples.
+        """
+        self.example_id = example_id
+        self.question = question
+        self.contexts = contexts
+        self.endings = endings
+        self.label = label
+
+
+class InputFeatures(object):
+    def __init__(self,
+                 example_id,
+                 choices_features,
+                 label
+
+    ):
+        self.example_id = example_id
+        self.choices_features = [
+            {
+                'input_ids': input_ids,
+                'input_mask': input_mask,
+                'segment_ids': segment_ids
+            }
+            for _, input_ids, input_mask, segment_ids in choices_features
+        ]
+        self.label = label
+
+
+class DataProcessor(object):
+    """Base class for data converters for multiple choice data sets."""
+
+    def get_train_examples(self, data_dir):
+        """Gets a collection of `InputExample`s for the train set."""
+        raise NotImplementedError()
+
+    def get_dev_examples(self, data_dir):
+        """Gets a collection of `InputExample`s for the dev set."""
+        raise NotImplementedError()
+
+    def get_test_examples(self, data_dir):
+        """Gets a collection of `InputExample`s for the test set."""
+        raise NotImplementedError()
+
+    def get_labels(self):
+        """Gets the list of labels for this data set."""
+        raise NotImplementedError()
+
+
+class RaceProcessor(DataProcessor):
+    """Processor for the RACE data set."""
+
+    def get_train_examples(self, data_dir):
+        """See base class."""
+        logger.info("LOOKING AT {} train".format(data_dir))
+        high = os.path.join(data_dir, 'train/high')
+        middle = os.path.join(data_dir, 'train/middle')
+        high = self._read_txt(high)
+        middle = self._read_txt(middle)
+        return self._create_examples(high + middle, 'train')
+
+    def get_dev_examples(self, data_dir):
+        """See base class."""
+        logger.info("LOOKING AT {} dev".format(data_dir))
+        high = os.path.join(data_dir, 'dev/high')
+        middle = os.path.join(data_dir, 'dev/middle')
+        high = self._read_txt(high)
+        middle = self._read_txt(middle)
+        return self._create_examples(high + middle, 'dev')
+
+    def get_test_examples(self, data_dir):
+        """See base class."""
+        logger.info("LOOKING AT {} test".format(data_dir))
+        high = os.path.join(data_dir, 'test/high')
+        middle = os.path.join(data_dir, 'test/middle')
+        high = self._read_txt(high)
+        middle = self._read_txt(middle)
+        return self._create_examples(high + middle, 'test')
+
+    def get_labels(self):
+        """See base class."""
+        return ["0", "1", "2", "3"]
+
+    def _read_txt(self, input_dir):
+        lines = []
+        files = glob.glob(input_dir + "/*txt")
+        for file in tqdm.tqdm(files, desc="read files"):
+            with open(file, 'r', encoding='utf-8') as fin:
+                data_raw = json.load(fin)
+                data_raw["race_id"] = file
+                lines.append(data_raw)
+        return lines
+
+
+    def _create_examples(self, lines, set_type):
+        """Creates examples for the training and dev sets."""
+        examples = []
+        for (_, data_raw) in enumerate(lines):
+            race_id = "%s-%s" % (set_type, data_raw["race_id"])
+            article = data_raw["article"]
+            for i in range(len(data_raw["answers"])):
+                truth = str(ord(data_raw['answers'][i]) - ord('A'))
+                question = data_raw['questions'][i]
+                options = data_raw['options'][i]
+
+                examples.append(
+                    InputExample(
+                        example_id=race_id,
+                        question=question,
+                        contexts=[article, article, article, article], # this is not efficient but convenient
+                        endings=[options[0], options[1], options[2], options[3]],
+                        label=truth))
+        return examples
+
+class SwagProcessor(DataProcessor):
+    """Processor for the SWAG data set."""
+
+    def get_train_examples(self, data_dir):
+        """See base class."""
+        logger.info("LOOKING AT {} train".format(data_dir))
+        return self._create_examples(self._read_csv(os.path.join(data_dir, "train.csv")), "train")
+
+    def get_dev_examples(self, data_dir):
+        """See base class."""
+        logger.info("LOOKING AT {} dev".format(data_dir))
+        return self._create_examples(self._read_csv(os.path.join(data_dir, "val.csv")), "dev")
+
+    def get_test_examples(self, data_dir):
+        """See base class."""
+        logger.info("LOOKING AT {} dev".format(data_dir))
+        raise ValueError(
+            "For swag testing, the input file does not contain a label column. It can not be tested in current code"
+            "setting!"
+        )
+        return self._create_examples(self._read_csv(os.path.join(data_dir, "test.csv")), "test")
+    def get_labels(self):
+        """See base class."""
+        return ["0", "1", "2", "3"]
+
+    def _read_csv(self, input_file):
+        with open(input_file, 'r', encoding='utf-8') as f:
+            reader = csv.reader(f)
+            lines = []
+            for line in reader:
+                if sys.version_info[0] == 2:
+                    line = list(unicode(cell, 'utf-8') for cell in line)
+                lines.append(line)
+            return lines
+
+
+    def _create_examples(self, lines, type):
+        """Creates examples for the training and dev sets."""
+        if type == "train" and lines[0][-1] != 'label':
+            raise ValueError(
+                "For training, the input file must contain a label column."
+            )
+
+        examples = [
+            InputExample(
+                example_id=line[2],
+                question=line[5],  # in the swag dataset, the
+                # common beginning of each
+                # choice is stored in "sent2".
+                contexts = [line[4], line[4], line[4], line[4]],
+                endings = [line[7], line[8], line[9], line[10]],
+                label=line[11]
+            ) for line in lines[1:]  # we skip the line with the column names
+        ]
+
+        return examples
+
+
+class ArcProcessor(DataProcessor):
+    """Processor for the ARC data set (request from allennlp)."""
+
+    def get_train_examples(self, data_dir):
+        """See base class."""
+        logger.info("LOOKING AT {} train".format(data_dir))
+        return self._create_examples(self._read_json(os.path.join(data_dir, "train.jsonl")), "train")
+
+    def get_dev_examples(self, data_dir):
+        """See base class."""
+        logger.info("LOOKING AT {} dev".format(data_dir))
+        return self._create_examples(self._read_json(os.path.join(data_dir, "dev.jsonl")), "dev")
+
+    def get_test_examples(self, data_dir):
+        logger.info("LOOKING AT {} test".format(data_dir))
+        return self._create_examples(self._read_json(os.path.join(data_dir, "test.jsonl")), "test")
+
+    def get_labels(self):
+        """See base class."""
+        return ["0", "1", "2", "3"]
+
+    def _read_json(self, input_file):
+        with open(input_file, 'r', encoding='utf-8') as fin:
+            lines = fin.readlines()
+            return lines
+
+
+    def _create_examples(self, lines, type):
+        """Creates examples for the training and dev sets."""
+
+        #There are two types of labels. They should be normalized
+        def normalize(truth):
+            if truth in "ABCD":
+                return ord(truth) - ord("A")
+            elif truth in "1234":
+                return int(truth) - 1
+            else:
+                logger.info("truth ERROR! %s", str(truth))
+                return None
+
+        examples = []
+        three_choice = 0
+        four_choice = 0
+        five_choice = 0
+        other_choices = 0
+        # we deleted example which has more than or less than four choices
+        for line in tqdm.tqdm(lines, desc="read arc data"):
+            data_raw = json.loads(line.strip("\n"))
+            if len(data_raw["question"]["choices"]) == 3:
+                three_choice += 1
+                continue
+            elif len(data_raw["question"]["choices"]) == 5:
+                five_choice += 1
+                continue
+            elif len(data_raw["question"]["choices"]) != 4:
+                other_choices += 1
+                continue
+            four_choice += 1
+            truth = str(normalize(data_raw["answerKey"]))
+            assert truth != "None"
+            question_choices = data_raw["question"]
+            question = question_choices["stem"]
+            id = data_raw["id"]
+            options = question_choices["choices"]
+            if len(options) == 4:
+                examples.append(
+                    InputExample(
+                        example_id = id,
+                        question=question,
+                        contexts=[options[0]["para"].replace("_", ""), options[1]["para"].replace("_", ""),
+                                  options[2]["para"].replace("_", ""), options[3]["para"].replace("_", "")],
+                        endings=[options[0]["text"], options[1]["text"], options[2]["text"], options[3]["text"]],
+                        label=truth))
+
+        if type == "train":
+            assert len(examples) > 1
+            assert examples[0].label is not None
+        logger.info("len examples: %s}", str(len(examples)))
+        logger.info("Three choices: %s", str(three_choice))
+        logger.info("Five choices: %s", str(five_choice))
+        logger.info("Other choices: %s", str(other_choices))
+        logger.info("four choices: %s", str(four_choice))
+
+        return examples
+
+
+def convert_examples_to_features(examples, label_list, max_seq_length,
+                                 tokenizer,
+                                 cls_token_at_end=False,
+                                 cls_token='[CLS]',
+                                 cls_token_segment_id=1,
+                                 sep_token='[SEP]',
+                                 sequence_a_segment_id=0,
+                                 sequence_b_segment_id=1,
+                                 sep_token_extra=False,
+                                 pad_token_segment_id=0,
+                                 pad_on_left=False,
+                                 pad_token=0,
+                                 mask_padding_with_zero=True):
+    """ Loads a data file into a list of `InputBatch`s
+        `cls_token_at_end` define the location of the CLS token:
+            - False (Default, BERT/XLM pattern): [CLS] + A + [SEP] + B + [SEP]
+            - True (XLNet/GPT pattern): A + [SEP] + B + [SEP] + [CLS]
+        `cls_token_segment_id` define the segment id associated to the CLS token (0 for BERT, 2 for XLNet)
+    """
+
+    label_map = {label : i for i, label in enumerate(label_list)}
+
+    features = []
+    for (ex_index, example) in tqdm.tqdm(enumerate(examples), desc="convert examples to features"):
+        if ex_index % 10000 == 0:
+            logger.info("Writing example %d of %d" % (ex_index, len(examples)))
+        choices_features = []
+        for ending_idx, (context, ending) in enumerate(zip(example.contexts, example.endings)):
+            tokens_a = tokenizer.tokenize(context)
+            tokens_b = None
+            if example.question.find("_") != -1:
+                #this is for cloze question
+                tokens_b = tokenizer.tokenize(example.question.replace("_", ending))
+            else:
+                tokens_b = tokenizer.tokenize(example.question + " " + ending)
+                # you can add seq token between quesiotn and ending. This does not make too much difference.
+                # tokens_b = tokenizer.tokenize(example.question)
+                # tokens_b += [sep_token]
+                # if sep_token_extra:
+                #     tokens_b += [sep_token]
+                # tokens_b += tokenizer.tokenize(ending)
+
+            special_tokens_count = 4 if sep_token_extra else 3
+            _truncate_seq_pair(tokens_a, tokens_b, max_seq_length - special_tokens_count)
+
+            # The convention in BERT is:
+            # (a) For sequence pairs:
+            #  tokens:   [CLS] is this jack ##son ##ville ? [SEP] no it is not . [SEP]
+            #  type_ids:   0   0  0    0    0     0       0   0   1  1  1  1   1   1
+            # (b) For single sequences:
+            #  tokens:   [CLS] the dog is hairy . [SEP]
+            #  type_ids:   0   0   0   0  0     0   0
+            #
+            # Where "type_ids" are used to indicate whether this is the first
+            # sequence or the second sequence. The embedding vectors for `type=0` and
+            # `type=1` were learned during pre-training and are added to the wordpiece
+            # embedding vector (and position vector). This is not *strictly* necessary
+            # since the [SEP] token unambiguously separates the sequences, but it makes
+            # it easier for the model to learn the concept of sequences.
+            #
+            # For classification tasks, the first vector (corresponding to [CLS]) is
+            # used as as the "sentence vector". Note that this only makes sense because
+            # the entire model is fine-tuned.
+            tokens = tokens_a + [sep_token]
+            if sep_token_extra:
+                # roberta uses an extra separator b/w pairs of sentences
+                tokens += [sep_token]
+
+            segment_ids = [sequence_a_segment_id] * len(tokens)
+
+            if tokens_b:
+                tokens += tokens_b + [sep_token]
+                segment_ids += [sequence_b_segment_id] * (len(tokens_b) + 1)
+
+            if cls_token_at_end:
+                tokens = tokens + [cls_token]
+                segment_ids = segment_ids + [cls_token_segment_id]
+            else:
+                tokens = [cls_token] + tokens
+                segment_ids = [cls_token_segment_id] + segment_ids
+
+            input_ids = tokenizer.convert_tokens_to_ids(tokens)
+
+            # The mask has 1 for real tokens and 0 for padding tokens. Only real
+            # tokens are attended to.
+            input_mask = [1 if mask_padding_with_zero else 0] * len(input_ids)
+
+            # Zero-pad up to the sequence length.
+            padding_length = max_seq_length - len(input_ids)
+            if pad_on_left:
+                input_ids = ([pad_token] * padding_length) + input_ids
+                input_mask = ([0 if mask_padding_with_zero else 1] * padding_length) + input_mask
+                segment_ids = ([pad_token_segment_id] * padding_length) + segment_ids
+            else:
+                input_ids = input_ids + ([pad_token] * padding_length)
+                input_mask = input_mask + ([0 if mask_padding_with_zero else 1] * padding_length)
+                segment_ids = segment_ids + ([pad_token_segment_id] * padding_length)
+
+            assert len(input_ids) == max_seq_length
+            assert len(input_mask) == max_seq_length
+            assert len(segment_ids) == max_seq_length
+            choices_features.append((tokens, input_ids, input_mask, segment_ids))
+        label = label_map[example.label]
+
+        if ex_index < 2:
+            logger.info("*** Example ***")
+            logger.info("race_id: {}".format(example.example_id))
+            for choice_idx, (tokens, input_ids, input_mask, segment_ids) in enumerate(choices_features):
+                logger.info("choice: {}".format(choice_idx))
+                logger.info("tokens: {}".format(' '.join(tokens)))
+                logger.info("input_ids: {}".format(' '.join(map(str, input_ids))))
+                logger.info("input_mask: {}".format(' '.join(map(str, input_mask))))
+                logger.info("segment_ids: {}".format(' '.join(map(str, segment_ids))))
+                logger.info("label: {}".format(label))
+
+        features.append(
+            InputFeatures(
+                example_id = example.example_id,
+                choices_features = choices_features,
+                label = label
+            )
+        )
+
+    return features
+
+
+def _truncate_seq_pair(tokens_a, tokens_b, max_length):
+    """Truncates a sequence pair in place to the maximum length."""
+
+    # This is a simple heuristic which will always truncate the longer sequence
+    # one token at a time. This makes more sense than truncating an equal percent
+    # of tokens from each, since if one sequence is very short then each token
+    # that's truncated likely contains more information than a longer sequence.
+
+    # However, since we'd better not to remove tokens of options and questions, you can choose to use a bigger
+    # length or only pop from context
+    while True:
+        total_length = len(tokens_a) + len(tokens_b)
+        if total_length <= max_length:
+            break
+        if len(tokens_a) > len(tokens_b):
+            tokens_a.pop()
+        else:
+            logger.info('Attention! you are removing from token_b (swag task is ok). '
+                        'If you are training ARC and RACE (you are poping question + options), '
+                        'you need to try to use a bigger max seq length!')
+            tokens_b.pop()
+
+
+processors = {
+    "race": RaceProcessor,
+    "swag": SwagProcessor,
+    "arc": ArcProcessor
+}
+
+
+GLUE_TASKS_NUM_LABELS = {
+    "race", 4,
+    "swag", 4,
+    "arc", 4
+}

pytorch_transformers/__init__.py

@@ -54,13 +54,13 @@ from .modeling_gpt2 import (GPT2PreTrainedModel, GPT2Model,
                             GPT2LMHeadModel, GPT2DoubleHeadsModel,
                             load_tf_weights_in_gpt2, GPT2_PRETRAINED_MODEL_ARCHIVE_MAP)
 from .modeling_xlnet import (XLNetPreTrainedModel, XLNetModel, XLNetLMHeadModel,
-                             XLNetForSequenceClassification, XLNetForQuestionAnswering,
+                             XLNetForSequenceClassification, XLNetForQuestionAnswering, XLNetForMultipleChoice,
                              load_tf_weights_in_xlnet, XLNET_PRETRAINED_MODEL_ARCHIVE_MAP)
 from .modeling_xlm import (XLMPreTrainedModel , XLMModel,
                            XLMWithLMHeadModel, XLMForSequenceClassification,
                            XLMForQuestionAnswering, XLM_PRETRAINED_MODEL_ARCHIVE_MAP)
 from .modeling_roberta import (RobertaForMaskedLM, RobertaModel, RobertaForSequenceClassification,
-                               ROBERTA_PRETRAINED_MODEL_ARCHIVE_MAP)
+                               RobertaForMultipleChoice, ROBERTA_PRETRAINED_MODEL_ARCHIVE_MAP)
 from .modeling_distilbert import (DistilBertForMaskedLM, DistilBertModel,
                                DistilBertForSequenceClassification, DistilBertForQuestionAnswering,
                                DISTILBERT_PRETRAINED_MODEL_ARCHIVE_MAP)

pytorch_transformers/modeling_roberta.py

@@ -296,7 +296,7 @@ class RobertaForSequenceClassification(BertPreTrainedModel):
 
     Examples::
 
-        tokenizer = RoertaTokenizer.from_pretrained('roberta-base')
+        tokenizer = RobertaTokenizer.from_pretrained('roberta-base')
         model = RobertaForSequenceClassification.from_pretrained('roberta-base')
         input_ids = torch.tensor(tokenizer.encode("Hello, my dog is cute")).unsqueeze(0)  # Batch size 1
         labels = torch.tensor([1]).unsqueeze(0)  # Batch size 1
@@ -338,6 +338,113 @@ 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)
+class RobertaForMultipleChoice(BertPreTrainedModel):
+    r"""
+    Inputs:
+        **input_ids**: ``torch.LongTensor`` of shape ``(batch_size, num_choices, sequence_length)``:
+            Indices of input sequence tokens in the vocabulary.
+            The second dimension of the input (`num_choices`) indicates the number of choices to score.
+            To match pre-training, RoBerta input sequence should be formatted with [CLS] and [SEP] tokens as follows:
+
+            (a) For sequence pairs:
+
+                ``tokens:         [CLS] is this jack ##son ##ville ? [SEP] [SEP] no it is not . [SEP]``
+
+                ``token_type_ids:   0   0  0    0    0     0       0   0   0     1  1  1  1   1   1``
+
+            (b) For single sequences:
+
+                ``tokens:         [CLS] the dog is hairy . [SEP]``
+
+                ``token_type_ids:   0   0   0   0  0     0   0``
+
+            Indices can be obtained using :class:`pytorch_transformers.BertTokenizer`.
+            See :func:`pytorch_transformers.PreTrainedTokenizer.encode` and
+            :func:`pytorch_transformers.PreTrainedTokenizer.convert_tokens_to_ids` for details.
+        **token_type_ids**: (`optional`) ``torch.LongTensor`` of shape ``(batch_size, num_choices, sequence_length)``:
+            Segment token indices to indicate first and second portions of the inputs.
+            The second dimension of the input (`num_choices`) indicates the number of choices to score.
+            Indices are selected in ``[0, 1]``: ``0`` corresponds to a `sentence A` token, ``1``
+        **attention_mask**: (`optional`) ``torch.FloatTensor`` of shape ``(batch_size, num_choices, sequence_length)``:
+            Mask to avoid performing attention on padding token indices.
+            The second dimension of the input (`num_choices`) indicates the number of choices to score.
+            Mask values selected in ``[0, 1]``:
+            ``1`` for tokens that are NOT MASKED, ``0`` for MASKED tokens.
+        **head_mask**: (`optional`) ``torch.FloatTensor`` of shape ``(num_heads,)`` or ``(num_layers, num_heads)``:
+            Mask to nullify selected heads of the self-attention modules.
+            Mask values selected in ``[0, 1]``:
+            ``1`` indicates the head is **not masked**, ``0`` indicates the head is **masked**.
+        **labels**: (`optional`) ``torch.LongTensor`` of shape ``(batch_size,)``:
+            Labels for computing the multiple choice classification loss.
+            Indices should be in ``[0, ..., num_choices]`` where `num_choices` is the size of the second dimension
+            of the input tensors. (see `input_ids` above)
+
+    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.
+        **classification_scores**: ``torch.FloatTensor`` of shape ``(batch_size, num_choices)`` where `num_choices` is the size of the second dimension
+            of the input tensors. (see `input_ids` above).
+            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 = RobertaForMultipleChoice.from_pretrained('roberta-base')
+        choices = ["Hello, my dog is cute", "Hello, my cat is amazing"]
+        input_ids = torch.tensor([tokenizer.encode(s, add_special_tokens=True) for s in choices]).unsqueeze(0)  # Batch size 1, 2 choices
+        labels = torch.tensor(1).unsqueeze(0)  # Batch size 1
+        outputs = model(input_ids, labels=labels)
+        loss, classification_scores = outputs[:2]
+
+    """
+    config_class = RobertaConfig
+    pretrained_model_archive_map = ROBERTA_PRETRAINED_MODEL_ARCHIVE_MAP
+    base_model_prefix = "roberta"
+
+    def __init__(self, config):
+        super(RobertaForMultipleChoice, self).__init__(config)
+
+        self.roberta = RobertaModel(config)
+        self.dropout = nn.Dropout(config.hidden_dropout_prob)
+        self.classifier = nn.Linear(config.hidden_size, 1)
+
+        self.init_weights()
+
+    def forward(self, input_ids, token_type_ids=None, attention_mask=None, labels=None,
+                position_ids=None, head_mask=None):
+        num_choices = input_ids.shape[1]
+
+        flat_input_ids = input_ids.view(-1, input_ids.size(-1))
+        flat_position_ids = position_ids.view(-1, position_ids.size(-1)) if position_ids is not None else None
+        flat_token_type_ids = token_type_ids.view(-1, token_type_ids.size(-1)) if token_type_ids is not None else None
+        flat_attention_mask = attention_mask.view(-1, attention_mask.size(-1)) if attention_mask is not None else None
+        outputs = self.roberta(flat_input_ids, position_ids=flat_position_ids, token_type_ids=flat_token_type_ids,
+                            attention_mask=flat_attention_mask, head_mask=head_mask)
+        pooled_output = outputs[1]
+
+        pooled_output = self.dropout(pooled_output)
+        logits = self.classifier(pooled_output)
+        reshaped_logits = logits.view(-1, num_choices)
+
+        outputs = (reshaped_logits,) + outputs[2:]  # add hidden states and attention if they are here
+
+        if labels is not None:
+            loss_fct = CrossEntropyLoss()
+            loss = loss_fct(reshaped_logits, labels)
+            outputs = (loss,) + outputs
+
+        return outputs  # (loss), reshaped_logits, (hidden_states), (attentions)
+
 
 
 class RobertaClassificationHead(nn.Module):

pytorch_transformers/modeling_xlnet.py

@@ -1011,6 +1011,97 @@ class XLNetForSequenceClassification(XLNetPreTrainedModel):
 
         return outputs  # return (loss), logits, mems, (hidden states), (attentions)
 
+@add_start_docstrings("""XLNet Model with a multiple choice classification head on top (a linear layer on top of
+    the pooled output and a softmax) e.g. for RACE/SWAG tasks. """,
+    XLNET_START_DOCSTRING, XLNET_INPUTS_DOCSTRING)
+class XLNetForMultipleChoice(XLNetPreTrainedModel):
+    r"""
+    Inputs:
+        **input_ids**: ``torch.LongTensor`` of shape ``(batch_size, num_choices, sequence_length)``:
+            Indices of input sequence tokens in the vocabulary.
+            The second dimension of the input (`num_choices`) indicates the number of choices to scores.
+        **token_type_ids**: (`optional`) ``torch.LongTensor`` of shape ``(batch_size, num_choices, sequence_length)``:
+            Segment token indices to indicate first and second portions of the inputs.
+            The second dimension of the input (`num_choices`) indicates the number of choices to score.
+            Indices are selected in ``[0, 1]``: ``0`` corresponds to a `sentence A` token, ``1``
+        **attention_mask**: (`optional`) ``torch.FloatTensor`` of shape ``(batch_size, num_choices, sequence_length)``:
+            Mask to avoid performing attention on padding token indices.
+            The second dimension of the input (`num_choices`) indicates the number of choices to score.
+            Mask values selected in ``[0, 1]``:
+            ``1`` for tokens that are NOT MASKED, ``0`` for MASKED tokens.
+        **head_mask**: (`optional`) ``torch.FloatTensor`` of shape ``(num_heads,)`` or ``(num_layers, num_heads)``:
+            Mask to nullify selected heads of the self-attention modules.
+            Mask values selected in ``[0, 1]``:
+            ``1`` indicates the head is **not masked**, ``0`` indicates the head is **masked**.
+        **labels**: (`optional`) ``torch.LongTensor`` of shape ``(batch_size,)``:
+            Labels for computing the multiple choice classification loss.
+            Indices should be in ``[0, ..., num_choices]`` where `num_choices` is the size of the second dimension
+            of the input tensors. (see `input_ids` above)
+
+    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.
+        **classification_scores**: ``torch.FloatTensor`` of shape ``(batch_size, num_choices)`` where `num_choices` is the size of the second dimension
+            of the input tensors. (see `input_ids` above).
+            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 = XLNetTokenizer.from_pretrained('xlnet-base-cased')
+        model = XLNetForMultipleChoice.from_pretrained('xlnet-base-cased')
+        choices = ["Hello, my dog is cute", "Hello, my cat is amazing"]
+        input_ids = torch.tensor([tokenizer.encode(s) for s in choices]).unsqueeze(0)  # Batch size 1, 2 choices
+        labels = torch.tensor(1).unsqueeze(0)  # Batch size 1
+        outputs = model(input_ids, labels=labels)
+        loss, classification_scores = outputs[:2]
+
+    """
+    def __init__(self, config):
+        super(XLNetForMultipleChoice, self).__init__(config)
+
+        self.transformer = XLNetModel(config)
+        self.sequence_summary = SequenceSummary(config)
+        self.logits_proj = nn.Linear(config.d_model, 1)
+
+        self.init_weights()
+
+    def forward(self, input_ids, token_type_ids=None, input_mask=None, attention_mask=None,
+                mems=None, perm_mask=None, target_mapping=None,
+                labels=None, head_mask=None):
+        num_choices = input_ids.shape[1]
+
+        flat_input_ids = input_ids.view(-1, input_ids.size(-1))
+        flat_token_type_ids = token_type_ids.view(-1, token_type_ids.size(-1)) if token_type_ids is not None else None
+        flat_attention_mask = attention_mask.view(-1, attention_mask.size(-1)) if attention_mask is not None else None
+        flat_input_mask = input_mask.view(-1, input_mask.size(-1)) if input_mask is not None else None
+
+        transformer_outputs = self.transformer(flat_input_ids, token_type_ids=flat_token_type_ids,
+                                               input_mask=flat_input_mask, attention_mask=flat_attention_mask,
+                                               mems=mems, perm_mask=perm_mask, target_mapping=target_mapping,
+                                               head_mask=head_mask)
+
+
+        output = transformer_outputs[0]
+
+        output = self.sequence_summary(output)
+        logits = self.logits_proj(output)
+        reshaped_logits = logits.view(-1, num_choices)
+        outputs = (reshaped_logits,) + transformer_outputs[1:]  # Keep mems, hidden states, attentions if there are in it
+
+        if labels is not None:
+            loss_fct = CrossEntropyLoss()
+            loss = loss_fct(reshaped_logits, labels.view(-1))
+            outputs = (loss,) + outputs
+
+        return outputs  # return (loss), logits, mems, (hidden states), (attentions)
+
 
 @add_start_docstrings("""XLNet Model with a span classification head on top for extractive question-answering tasks like SQuAD (a linear layers on top of
     the hidden-states output to compute `span start logits` and `span end logits`). """,
@@ -1066,7 +1157,7 @@ class XLNetForQuestionAnswering(XLNetPreTrainedModel):
 
     Examples::
 
-        tokenizer = XLMTokenizer.from_pretrained('xlm-mlm-en-2048')
+        tokenizer =  XLNetTokenizer.from_pretrained('xlnet-large-cased')
         model = XLMForQuestionAnswering.from_pretrained('xlnet-large-cased')
         input_ids = torch.tensor(tokenizer.encode("Hello, my dog is cute")).unsqueeze(0)  # Batch size 1
         start_positions = torch.tensor([1])