diff --git a/README.md b/README.md index 720ddc3478..ba12886e54 100644 --- a/README.md +++ b/README.md @@ -52,8 +52,9 @@ This package comprises the following classes that can be imported in Python and - [`BertForNextSentencePrediction`](./pytorch_pretrained_bert/modeling.py#L752) - BERT Transformer with the pre-trained next sentence prediction classifier on top (**fully pre-trained**), - [`BertForPreTraining`](./pytorch_pretrained_bert/modeling.py#L620) - BERT Transformer with masked language modeling head and next sentence prediction classifier on top (**fully pre-trained**), - [`BertForSequenceClassification`](./pytorch_pretrained_bert/modeling.py#L814) - BERT Transformer with a sequence classification head on top (BERT Transformer is **pre-trained**, the sequence classification head **is only initialized and has to be trained**), - - [`BertForTokenClassification`](./pytorch_pretrained_bert/modeling.py#L880) - BERT Transformer with a token classification head on top (BERT Transformer is **pre-trained**, the token classification head **is only initialized and has to be trained**), - - [`BertForQuestionAnswering`](./pytorch_pretrained_bert/modeling.py#L946) - BERT Transformer with a token classification head on top (BERT Transformer is **pre-trained**, the token classification head **is only initialized and has to be trained**). + - [`BertForMultipleChoice`](./pytorch_pretrained_bert/modeling.py#L880) - BERT Transformer with a multiple choice head on top (used for task like Swag) (BERT Transformer is **pre-trained**, the sequence classification head **is only initialized and has to be trained**), + - [`BertForTokenClassification`](./pytorch_pretrained_bert/modeling.py#L949) - BERT Transformer with a token classification head on top (BERT Transformer is **pre-trained**, the token classification head **is only initialized and has to be trained**), + - [`BertForQuestionAnswering`](./pytorch_pretrained_bert/modeling.py#L1015) - BERT Transformer with a token classification head on top (BERT Transformer is **pre-trained**, the token classification head **is only initialized and has to be trained**). - Three tokenizers (in the [`tokenization.py`](./pytorch_pretrained_bert/tokenization.py) file): - `BasicTokenizer` - basic tokenization (punctuation splitting, lower casing, etc.), @@ -68,10 +69,11 @@ This package comprises the following classes that can be imported in Python and The repository further comprises: -- Three examples on how to use Bert (in the [`examples` folder](./examples)): +- Four examples on how to use Bert (in the [`examples` folder](./examples)): - [`extract_features.py`](./examples/extract_features.py) - Show how to extract hidden states from an instance of `BertModel`, - [`run_classifier.py`](./examples/run_classifier.py) - Show how to fine-tune an instance of `BertForSequenceClassification` on GLUE's MRPC task, - [`run_squad.py`](./examples/run_squad.py) - Show how to fine-tune an instance of `BertForQuestionAnswering` on SQuAD v1.0 task. + - [`run_swag.py`](./examples/run_swag.py) - Show how to fine-tune an instance of `BertForMultipleChoice` on Swag task. These examples are detailed in the [Examples](#examples) section of this readme. @@ -278,13 +280,23 @@ The sequence-level classifier is a linear layer that takes as input the last hid An example on how to use this class is given in the [`run_classifier.py`](./examples/run_classifier.py) script which can be used to fine-tune a single sequence (or pair of sequence) classifier using BERT, for example for the MRPC task. -#### 6. `BertForTokenClassification` +#### 6. `BertForMultipleChoice` + +`BertForMultipleChoice` is a fine-tuning model that includes `BertModel` and a linear layer on top of the `BertModel`. + +The linear layer outputs a single value for each choice of a multiple choice problem, then all the outputs corresponding to an instance are passed through a softmax to get the model choice. + +This implementation is largely inspired by the work of OpenAI in [Improving Language Understanding by Generative Pre-Training](https://blog.openai.com/language-unsupervised/) and the answer of Jacob Devlin in the following [issue](https://github.com/google-research/bert/issues/38). + +An example on how to use this class is given in the [`run_swag.py`](./examples/run_swag.py) script which can be used to fine-tune a multiple choice classifier using BERT, for example for the Swag task. + +#### 7. `BertForTokenClassification` `BertForTokenClassification` is a fine-tuning model that includes `BertModel` and a token-level classifier on top of the `BertModel`. The token-level classifier is a linear layer that takes as input the last hidden state of the sequence. -#### 7. `BertForQuestionAnswering` +#### 8. `BertForQuestionAnswering` `BertForQuestionAnswering` is a fine-tuning model that includes `BertModel` with a token-level classifiers on top of the full sequence of last hidden states. @@ -420,6 +432,32 @@ Training with the previous hyper-parameters gave us the following results: {"f1": 88.52381567990474, "exact_match": 81.22043519394512} ``` +The data for Swag can be downloaded by cloning the following [repository](https://github.com/rowanz/swagaf) + +```shell +export SWAG_DIR=/path/to/SWAG + +python run_swag.py \ + --bert_model bert-base-uncased \ + --do_train \ + --do_eval \ + --data_dir $SWAG_DIR/data + --train_batch_size 16 \ + --learning_rate 2e-5 \ + --num_train_epochs 3.0 \ + --max_seq_length 80 \ + --output_dir /tmp/swag_output/ + --gradient_accumulation_steps 4 +``` + +Training with the previous hyper-parameters gave us the following results: +``` +eval_accuracy = 0.8062081375587323 +eval_loss = 0.5966546792367169 +global_step = 13788 +loss = 0.06423990014260186 +``` + ## Fine-tuning BERT-large on GPUs The options we list above allow to fine-tune BERT-large rather easily on GPU(s) instead of the TPU used by the original implementation. diff --git a/examples/run_swag.py b/examples/run_swag.py new file mode 100644 index 0000000000..88297bf801 --- /dev/null +++ b/examples/run_swag.py @@ -0,0 +1,544 @@ +# coding=utf-8 +# Copyright 2018 The Google AI Language Team Authors and The HugginFace 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. +"""BERT finetuning runner.""" + +import logging +import os +import argparse +import random +from tqdm import tqdm, trange +import csv + +import numpy as np +import torch +from torch.utils.data import TensorDataset, DataLoader, RandomSampler, SequentialSampler +from torch.utils.data.distributed import DistributedSampler + +from pytorch_pretrained_bert.tokenization import BertTokenizer +from pytorch_pretrained_bert.modeling import BertForMultipleChoice +from pytorch_pretrained_bert.optimization import BertAdam +from pytorch_pretrained_bert.file_utils import PYTORCH_PRETRAINED_BERT_CACHE + +logging.basicConfig(format = '%(asctime)s - %(levelname)s - %(name)s - %(message)s', + datefmt = '%m/%d/%Y %H:%M:%S', + level = logging.INFO) +logger = logging.getLogger(__name__) + + +class SwagExample(object): + """A single training/test example for the SWAG dataset.""" + def __init__(self, + swag_id, + context_sentence, + start_ending, + ending_0, + ending_1, + ending_2, + ending_3, + label = None): + self.swag_id = swag_id + self.context_sentence = context_sentence + self.start_ending = start_ending + self.endings = [ + ending_0, + ending_1, + ending_2, + ending_3, + ] + self.label = label + + def __str__(self): + return self.__repr__() + + def __repr__(self): + l = [ + f"swag_id: {self.swag_id}", + f"context_sentence: {self.context_sentence}", + f"start_ending: {self.start_ending}", + f"ending_0: {self.endings[0]}", + f"ending_1: {self.endings[1]}", + f"ending_2: {self.endings[2]}", + f"ending_3: {self.endings[3]}", + ] + + if self.label is not None: + l.append(f"label: {self.label}") + + return ", ".join(l) + + +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 + + +def read_swag_examples(input_file, is_training): + with open(input_file, 'r') as f: + reader = csv.reader(f) + lines = list(reader) + + if is_training and lines[0][-1] != 'label': + raise ValueError( + "For training, the input file must contain a label column." + ) + + examples = [ + SwagExample( + swag_id = line[2], + context_sentence = line[4], + start_ending = line[5], # in the swag dataset, the + # common beginning of each + # choice is stored in "sent2". + ending_0 = line[7], + ending_1 = line[8], + ending_2 = line[9], + ending_3 = line[10], + label = int(line[11]) if is_training else None + ) for line in lines[1:] # we skip the line with the column names + ] + + return examples + +def convert_examples_to_features(examples, tokenizer, max_seq_length, + is_training): + """Loads a data file into a list of `InputBatch`s.""" + + # Swag is a multiple choice task. To perform this task using Bert, + # we will use the formatting proposed in "Improving Language + # Understanding by Generative Pre-Training" and suggested by + # @jacobdevlin-google in this issue + # https://github.com/google-research/bert/issues/38. + # + # Each choice will correspond to a sample on which we run the + # inference. For a given Swag example, we will create the 4 + # following inputs: + # - [CLS] context [SEP] choice_1 [SEP] + # - [CLS] context [SEP] choice_2 [SEP] + # - [CLS] context [SEP] choice_3 [SEP] + # - [CLS] context [SEP] choice_4 [SEP] + # The model will output a single value for each input. To get the + # final decision of the model, we will run a softmax over these 4 + # outputs. + features = [] + for example_index, example in enumerate(examples): + context_tokens = tokenizer.tokenize(example.context_sentence) + start_ending_tokens = tokenizer.tokenize(example.start_ending) + + choices_features = [] + for ending_index, ending in enumerate(example.endings): + # We create a copy of the context tokens in order to be + # able to shrink it according to ending_tokens + context_tokens_choice = context_tokens[:] + ending_tokens = start_ending_tokens + tokenizer.tokenize(ending) + # Modifies `context_tokens_choice` and `ending_tokens` in + # place so that the total length is less than the + # specified length. Account for [CLS], [SEP], [SEP] with + # "- 3" + _truncate_seq_pair(context_tokens_choice, ending_tokens, max_seq_length - 3) + + tokens = ["[CLS]"] + context_tokens_choice + ["[SEP]"] + ending_tokens + ["[SEP]"] + segment_ids = [0] * (len(context_tokens_choice) + 2) + [1] * (len(ending_tokens) + 1) + + input_ids = tokenizer.convert_tokens_to_ids(tokens) + input_mask = [1] * len(input_ids) + + # Zero-pad up to the sequence length. + padding = [0] * (max_seq_length - len(input_ids)) + input_ids += padding + input_mask += padding + segment_ids += padding + + 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 = example.label + if example_index < 5: + logger.info("*** Example ***") + logger.info(f"swag_id: {example.swag_id}") + for choice_idx, (tokens, input_ids, input_mask, segment_ids) in enumerate(choices_features): + logger.info(f"choice: {choice_idx}") + logger.info(f"tokens: {' '.join(tokens)}") + logger.info(f"input_ids: {' '.join(map(str, input_ids))}") + logger.info(f"input_mask: {' '.join(map(str, input_mask))}") + logger.info(f"segment_ids: {' '.join(map(str, segment_ids))}") + if is_training: + logger.info(f"label: {label}") + + features.append( + InputFeatures( + example_id = example.swag_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. + 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: + tokens_b.pop() + +def accuracy(out, labels): + outputs = np.argmax(out, axis=1) + return np.sum(outputs == labels) + +def select_field(features, field): + return [ + [ + choice[field] + for choice in feature.choices_features + ] + for feature in features + ] + +def copy_optimizer_params_to_model(named_params_model, named_params_optimizer): + """ Utility function for optimize_on_cpu and 16-bits training. + Copy the parameters optimized on CPU/RAM back to the model on GPU + """ + for (name_opti, param_opti), (name_model, param_model) in zip(named_params_optimizer, named_params_model): + if name_opti != name_model: + logger.error("name_opti != name_model: {} {}".format(name_opti, name_model)) + raise ValueError + param_model.data.copy_(param_opti.data) + +def set_optimizer_params_grad(named_params_optimizer, named_params_model, test_nan=False): + """ Utility function for optimize_on_cpu and 16-bits training. + Copy the gradient of the GPU parameters to the CPU/RAMM copy of the model + """ + is_nan = False + for (name_opti, param_opti), (name_model, param_model) in zip(named_params_optimizer, named_params_model): + if name_opti != name_model: + logger.error("name_opti != name_model: {} {}".format(name_opti, name_model)) + raise ValueError + if param_model.grad is not None: + if test_nan and torch.isnan(param_model.grad).sum() > 0: + is_nan = True + if param_opti.grad is None: + param_opti.grad = torch.nn.Parameter(param_opti.data.new().resize_(*param_opti.data.size())) + param_opti.grad.data.copy_(param_model.grad.data) + else: + param_opti.grad = None + return is_nan + +def main(): + parser = argparse.ArgumentParser() + + ## Required parameters + parser.add_argument("--data_dir", + default=None, + type=str, + required=True, + help="The input data dir. Should contain the .csv files (or other data files) for the task.") + parser.add_argument("--bert_model", default=None, type=str, required=True, + help="Bert pre-trained model selected in the list: bert-base-uncased, " + "bert-large-uncased, bert-base-cased, bert-base-multilingual, bert-base-chinese.") + parser.add_argument("--output_dir", + default=None, + type=str, + required=True, + help="The output directory where the model checkpoints will be written.") + + ## Other parameters + parser.add_argument("--max_seq_length", + default=128, + type=int, + help="The maximum total input sequence length after WordPiece tokenization. \n" + "Sequences longer than this will be truncated, and sequences shorter \n" + "than this will be padded.") + parser.add_argument("--do_train", + default=False, + action='store_true', + help="Whether to run training.") + parser.add_argument("--do_eval", + default=False, + action='store_true', + help="Whether to run eval on the dev set.") + parser.add_argument("--do_lower_case", + default=False, + action='store_true', + help="Set this flag if you are using an uncased model.") + parser.add_argument("--train_batch_size", + default=32, + type=int, + help="Total batch size for training.") + parser.add_argument("--eval_batch_size", + default=8, + type=int, + help="Total batch size for eval.") + parser.add_argument("--learning_rate", + default=5e-5, + type=float, + help="The initial learning rate for Adam.") + parser.add_argument("--num_train_epochs", + default=3.0, + type=float, + help="Total number of training epochs to perform.") + parser.add_argument("--warmup_proportion", + default=0.1, + type=float, + help="Proportion of training to perform linear learning rate warmup for. " + "E.g., 0.1 = 10%% of training.") + parser.add_argument("--no_cuda", + default=False, + action='store_true', + help="Whether not to use CUDA when available") + parser.add_argument("--local_rank", + type=int, + default=-1, + help="local_rank for distributed training on gpus") + parser.add_argument('--seed', + type=int, + default=42, + help="random seed for initialization") + parser.add_argument('--gradient_accumulation_steps', + type=int, + default=1, + help="Number of updates steps to accumulate before performing a backward/update pass.") + parser.add_argument('--optimize_on_cpu', + default=False, + action='store_true', + help="Whether to perform optimization and keep the optimizer averages on CPU") + parser.add_argument('--fp16', + default=False, + action='store_true', + help="Whether to use 16-bit float precision instead of 32-bit") + parser.add_argument('--loss_scale', + type=float, default=128, + help='Loss scaling, positive power of 2 values can improve fp16 convergence.') + + args = parser.parse_args() + + if args.local_rank == -1 or args.no_cuda: + device = torch.device("cuda" if torch.cuda.is_available() and not args.no_cuda else "cpu") + n_gpu = torch.cuda.device_count() + else: + device = torch.device("cuda", args.local_rank) + n_gpu = 1 + # Initializes the distributed backend which will take care of sychronizing nodes/GPUs + torch.distributed.init_process_group(backend='nccl') + if args.fp16: + logger.info("16-bits training currently not supported in distributed training") + args.fp16 = False # (see https://github.com/pytorch/pytorch/pull/13496) + logger.info("device %s n_gpu %d distributed training %r", device, n_gpu, bool(args.local_rank != -1)) + + if args.gradient_accumulation_steps < 1: + raise ValueError("Invalid gradient_accumulation_steps parameter: {}, should be >= 1".format( + args.gradient_accumulation_steps)) + + args.train_batch_size = int(args.train_batch_size / args.gradient_accumulation_steps) + + random.seed(args.seed) + np.random.seed(args.seed) + torch.manual_seed(args.seed) + if n_gpu > 0: + torch.cuda.manual_seed_all(args.seed) + + if not args.do_train and not args.do_eval: + raise ValueError("At least one of `do_train` or `do_eval` must be True.") + + if os.path.exists(args.output_dir) and os.listdir(args.output_dir): + raise ValueError("Output directory ({}) already exists and is not empty.".format(args.output_dir)) + os.makedirs(args.output_dir, exist_ok=True) + + tokenizer = BertTokenizer.from_pretrained(args.bert_model, do_lower_case=args.do_lower_case) + + train_examples = None + num_train_steps = None + if args.do_train: + train_examples = read_swag_examples(os.path.join(args.data_dir, 'train.csv'), is_training = True) + num_train_steps = int( + len(train_examples) / args.train_batch_size / args.gradient_accumulation_steps * args.num_train_epochs) + + # Prepare model + model = BertForMultipleChoice.from_pretrained(args.bert_model, + cache_dir=PYTORCH_PRETRAINED_BERT_CACHE / 'distributed_{}'.format(args.local_rank), + num_choices = 4 + ) + if args.fp16: + model.half() + model.to(device) + if args.local_rank != -1: + model = torch.nn.parallel.DistributedDataParallel(model, device_ids=[args.local_rank], + output_device=args.local_rank) + elif n_gpu > 1: + model = torch.nn.DataParallel(model) + + # Prepare optimizer + if args.fp16: + param_optimizer = [(n, param.clone().detach().to('cpu').float().requires_grad_()) \ + for n, param in model.named_parameters()] + elif args.optimize_on_cpu: + param_optimizer = [(n, param.clone().detach().to('cpu').requires_grad_()) \ + for n, param in model.named_parameters()] + else: + param_optimizer = list(model.named_parameters()) + no_decay = ['bias', 'gamma', 'beta'] + optimizer_grouped_parameters = [ + {'params': [p for n, p in param_optimizer if not any(nd in n for nd in no_decay)], 'weight_decay_rate': 0.01}, + {'params': [p for n, p in param_optimizer if any(nd in n for nd in no_decay)], 'weight_decay_rate': 0.0} + ] + t_total = num_train_steps + if args.local_rank != -1: + t_total = t_total // torch.distributed.get_world_size() + optimizer = BertAdam(optimizer_grouped_parameters, + lr=args.learning_rate, + warmup=args.warmup_proportion, + t_total=t_total) + + global_step = 0 + if args.do_train: + train_features = convert_examples_to_features( + train_examples, tokenizer, args.max_seq_length, True) + logger.info("***** Running training *****") + logger.info(" Num examples = %d", len(train_examples)) + logger.info(" Batch size = %d", args.train_batch_size) + logger.info(" Num steps = %d", num_train_steps) + all_input_ids = torch.tensor(select_field(train_features, 'input_ids'), dtype=torch.long) + all_input_mask = torch.tensor(select_field(train_features, 'input_mask'), dtype=torch.long) + all_segment_ids = torch.tensor(select_field(train_features, 'segment_ids'), dtype=torch.long) + all_label = torch.tensor([f.label for f in train_features], dtype=torch.long) + train_data = TensorDataset(all_input_ids, all_input_mask, all_segment_ids, all_label) + if args.local_rank == -1: + train_sampler = RandomSampler(train_data) + else: + train_sampler = DistributedSampler(train_data) + train_dataloader = DataLoader(train_data, sampler=train_sampler, batch_size=args.train_batch_size) + + model.train() + for _ in trange(int(args.num_train_epochs), desc="Epoch"): + tr_loss = 0 + nb_tr_examples, nb_tr_steps = 0, 0 + for step, batch in enumerate(tqdm(train_dataloader, desc="Iteration")): + batch = tuple(t.to(device) for t in batch) + input_ids, input_mask, segment_ids, label_ids = batch + loss = model(input_ids, segment_ids, input_mask, label_ids) + if n_gpu > 1: + loss = loss.mean() # mean() to average on multi-gpu. + if args.fp16 and args.loss_scale != 1.0: + # rescale loss for fp16 training + # see https://docs.nvidia.com/deeplearning/sdk/mixed-precision-training/index.html + loss = loss * args.loss_scale + if args.gradient_accumulation_steps > 1: + loss = loss / args.gradient_accumulation_steps + loss.backward() + tr_loss += loss.item() + nb_tr_examples += input_ids.size(0) + nb_tr_steps += 1 + if (step + 1) % args.gradient_accumulation_steps == 0: + if args.fp16 or args.optimize_on_cpu: + if args.fp16 and args.loss_scale != 1.0: + # scale down gradients for fp16 training + for param in model.parameters(): + if param.grad is not None: + param.grad.data = param.grad.data / args.loss_scale + is_nan = set_optimizer_params_grad(param_optimizer, model.named_parameters(), test_nan=True) + if is_nan: + logger.info("FP16 TRAINING: Nan in gradients, reducing loss scaling") + args.loss_scale = args.loss_scale / 2 + model.zero_grad() + continue + optimizer.step() + copy_optimizer_params_to_model(model.named_parameters(), param_optimizer) + else: + optimizer.step() + model.zero_grad() + global_step += 1 + + if args.do_eval and (args.local_rank == -1 or torch.distributed.get_rank() == 0): + eval_examples = read_swag_examples(os.path.join(args.data_dir, 'val.csv'), is_training = True) + eval_features = convert_examples_to_features( + eval_examples, tokenizer, args.max_seq_length, True) + logger.info("***** Running evaluation *****") + logger.info(" Num examples = %d", len(eval_examples)) + logger.info(" Batch size = %d", args.eval_batch_size) + all_input_ids = torch.tensor(select_field(eval_features, 'input_ids'), dtype=torch.long) + all_input_mask = torch.tensor(select_field(eval_features, 'input_mask'), dtype=torch.long) + all_segment_ids = torch.tensor(select_field(eval_features, 'segment_ids'), dtype=torch.long) + all_label = torch.tensor([f.label for f in eval_features], dtype=torch.long) + eval_data = TensorDataset(all_input_ids, all_input_mask, all_segment_ids, all_label) + # Run prediction for full data + eval_sampler = SequentialSampler(eval_data) + eval_dataloader = DataLoader(eval_data, sampler=eval_sampler, batch_size=args.eval_batch_size) + + model.eval() + eval_loss, eval_accuracy = 0, 0 + nb_eval_steps, nb_eval_examples = 0, 0 + for input_ids, input_mask, segment_ids, label_ids in eval_dataloader: + input_ids = input_ids.to(device) + input_mask = input_mask.to(device) + segment_ids = segment_ids.to(device) + label_ids = label_ids.to(device) + + with torch.no_grad(): + tmp_eval_loss = model(input_ids, segment_ids, input_mask, label_ids) + logits = model(input_ids, segment_ids, input_mask) + + logits = logits.detach().cpu().numpy() + label_ids = label_ids.to('cpu').numpy() + tmp_eval_accuracy = accuracy(logits, label_ids) + + eval_loss += tmp_eval_loss.mean().item() + eval_accuracy += tmp_eval_accuracy + + nb_eval_examples += input_ids.size(0) + nb_eval_steps += 1 + + eval_loss = eval_loss / nb_eval_steps + eval_accuracy = eval_accuracy / nb_eval_examples + + result = {'eval_loss': eval_loss, + 'eval_accuracy': eval_accuracy, + 'global_step': global_step, + 'loss': tr_loss/nb_tr_steps} + + output_eval_file = os.path.join(args.output_dir, "eval_results.txt") + with open(output_eval_file, "w") as writer: + logger.info("***** Eval results *****") + for key in sorted(result.keys()): + logger.info(" %s = %s", key, str(result[key])) + writer.write("%s = %s\n" % (key, str(result[key]))) + + +if __name__ == "__main__": + main() diff --git a/pytorch_pretrained_bert/__init__.py b/pytorch_pretrained_bert/__init__.py index fc9b15a12d..e1ecabf31d 100644 --- a/pytorch_pretrained_bert/__init__.py +++ b/pytorch_pretrained_bert/__init__.py @@ -1,7 +1,7 @@ from .tokenization import BertTokenizer, BasicTokenizer, WordpieceTokenizer from .modeling import (BertConfig, BertModel, BertForPreTraining, BertForMaskedLM, BertForNextSentencePrediction, - BertForSequenceClassification, BertForTokenClassification, - BertForQuestionAnswering) + BertForSequenceClassification, BertForMultipleChoice, + BertForTokenClassification, BertForQuestionAnswering) from .optimization import BertAdam from .file_utils import PYTORCH_PRETRAINED_BERT_CACHE diff --git a/pytorch_pretrained_bert/modeling.py b/pytorch_pretrained_bert/modeling.py index 3af5854072..e23e2c1a1c 100644 --- a/pytorch_pretrained_bert/modeling.py +++ b/pytorch_pretrained_bert/modeling.py @@ -877,6 +877,75 @@ class BertForSequenceClassification(PreTrainedBertModel): return logits +class BertForMultipleChoice(PreTrainedBertModel): + """BERT model for multiple choice tasks. + This module is composed of the BERT model with a linear layer on top of + the pooled output. + + Params: + `config`: a BertConfig class instance with the configuration to build a new model. + `num_choices`: the number of classes for the classifier. Default = 2. + + Inputs: + `input_ids`: a torch.LongTensor of shape [batch_size, num_choices, sequence_length] + with the word token indices in the vocabulary(see the tokens preprocessing logic in the scripts + `extract_features.py`, `run_classifier.py` and `run_squad.py`) + `token_type_ids`: an optional torch.LongTensor of shape [batch_size, num_choices, sequence_length] + with the token types indices selected in [0, 1]. Type 0 corresponds to a `sentence A` + and type 1 corresponds to a `sentence B` token (see BERT paper for more details). + `attention_mask`: an optional torch.LongTensor of shape [batch_size, num_choices, sequence_length] with indices + selected in [0, 1]. It's a mask to be used if the input sequence length is smaller than the max + input sequence length in the current batch. It's the mask that we typically use for attention when + a batch has varying length sentences. + `labels`: labels for the classification output: torch.LongTensor of shape [batch_size] + with indices selected in [0, ..., num_choices]. + + Outputs: + if `labels` is not `None`: + Outputs the CrossEntropy classification loss of the output with the labels. + if `labels` is `None`: + Outputs the classification logits of shape [batch_size, num_labels]. + + Example usage: + ```python + # Already been converted into WordPiece token ids + input_ids = torch.LongTensor([[[31, 51, 99], [15, 5, 0]], [[12, 16, 42], [14, 28, 57]]]) + input_mask = torch.LongTensor([[[1, 1, 1], [1, 1, 0]],[[1,1,0], [1, 0, 0]]]) + token_type_ids = torch.LongTensor([[[0, 0, 1], [0, 1, 0]],[[0, 1, 1], [0, 0, 1]]]) + config = BertConfig(vocab_size_or_config_json_file=32000, hidden_size=768, + num_hidden_layers=12, num_attention_heads=12, intermediate_size=3072) + + num_choices = 2 + + model = BertForMultipleChoice(config, num_choices) + logits = model(input_ids, token_type_ids, input_mask) + ``` + """ + def __init__(self, config, num_choices=2): + super(BertForMultipleChoice, self).__init__(config) + self.num_choices = num_choices + self.bert = BertModel(config) + self.dropout = nn.Dropout(config.hidden_dropout_prob) + self.classifier = nn.Linear(config.hidden_size, 1) + self.apply(self.init_bert_weights) + + def forward(self, input_ids, token_type_ids=None, attention_mask=None, labels=None): + 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)) + flat_attention_mask = attention_mask.view(-1, attention_mask.size(-1)) + _, pooled_output = self.bert(flat_input_ids, flat_token_type_ids, flat_attention_mask, output_all_encoded_layers=False) + pooled_output = self.dropout(pooled_output) + logits = self.classifier(pooled_output) + reshaped_logits = logits.view(-1, self.num_choices) + + if labels is not None: + loss_fct = CrossEntropyLoss() + loss = loss_fct(reshaped_logits, labels) + return loss + else: + return reshaped_logits + + class BertForTokenClassification(PreTrainedBertModel): """BERT model for token-level classification. This module is composed of the BERT model with a linear layer on top of