Source code for deeppavlov.models.torch_bert.torch_bert_squad

# Copyright 2017 Neural Networks and Deep Learning lab, MIPT
# 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
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.

import json
import math
from logging import getLogger
from pathlib import Path
from typing import List, Tuple, Optional, Dict

import numpy as np
import torch
from overrides import overrides
from transformers import BertForQuestionAnswering, BertConfig, BertTokenizer
from import InputFeatures

from deeppavlov import build_model
from deeppavlov.core.common.errors import ConfigError
from deeppavlov.core.commands.utils import expand_path
from deeppavlov.core.common.registry import register
from deeppavlov.core.models.estimator import Component
from deeppavlov.core.models.torch_model import TorchModel

logger = getLogger(__name__)

def softmax_mask(val, mask):
    INF = 1e30
    return -INF * (1 - + val

[docs]@register('torch_squad_bert_model') class TorchBertSQuADModel(TorchModel): """Bert-based on PyTorch model for SQuAD-like problem setting: It predicts start and end position of answer for given question and context. [CLS] token is used as no_answer. If model selects [CLS] token as most probable answer, it means that there is no answer in given context. Start and end position of answer are predicted by linear transformation of Bert outputs. Args: pretrained_bert: pretrained Bert checkpoint path or key title (e.g. "bert-base-uncased") attention_probs_keep_prob: keep_prob for Bert self-attention layers hidden_keep_prob: keep_prob for Bert hidden layers optimizer: optimizer name from `torch.optim` optimizer_parameters: dictionary with optimizer's parameters, e.g. {'lr': 0.1, 'weight_decay': 0.001, 'momentum': 0.9} bert_config_file: path to Bert configuration file, or None, if `pretrained_bert` is a string name learning_rate_drop_patience: how many validations with no improvements to wait learning_rate_drop_div: the divider of the learning rate after `learning_rate_drop_patience` unsuccessful validations load_before_drop: whether to load best model before dropping learning rate or not clip_norm: clip gradients by norm min_learning_rate: min value of learning rate if learning rate decay is used """ def __init__(self, pretrained_bert: str, attention_probs_keep_prob: Optional[float] = None, hidden_keep_prob: Optional[float] = None, optimizer: str = "AdamW", optimizer_parameters: dict = {"lr": 0.01, "weight_decay": 0.01, "betas": (0.9, 0.999), "eps": 1e-6}, bert_config_file: Optional[str] = None, learning_rate_drop_patience: int = 20, learning_rate_drop_div: float = 2.0, load_before_drop: bool = True, clip_norm: Optional[float] = None, min_learning_rate: float = 1e-06, **kwargs) -> None: self.attention_probs_keep_prob = attention_probs_keep_prob self.hidden_keep_prob = hidden_keep_prob self.clip_norm = clip_norm self.pretrained_bert = pretrained_bert self.bert_config_file = bert_config_file super().__init__(optimizer=optimizer, optimizer_parameters=optimizer_parameters, learning_rate_drop_patience=learning_rate_drop_patience, learning_rate_drop_div=learning_rate_drop_div, load_before_drop=load_before_drop, min_learning_rate=min_learning_rate, **kwargs)
[docs] def train_on_batch(self, features: List[InputFeatures], y_st: List[List[int]], y_end: List[List[int]]) -> Dict: """Train model on given batch. This method calls train_op using features and labels from y_st and y_end Args: features: batch of InputFeatures instances y_st: batch of lists of ground truth answer start positions y_end: batch of lists of ground truth answer end positions Returns: dict with loss and learning_rate values """ input_ids = [f.input_ids for f in features] input_masks = [f.attention_mask for f in features] input_type_ids = [f.token_type_ids for f in features] b_input_ids =, dim=0).to(self.device) b_input_masks =, dim=0).to(self.device) b_input_type_ids =, dim=0).to(self.device) y_st = [x[0] for x in y_st] y_end = [x[0] for x in y_end] b_y_st = torch.from_numpy(np.array(y_st)).to(self.device) b_y_end = torch.from_numpy(np.array(y_end)).to(self.device) self.optimizer.zero_grad() outputs = self.model(input_ids=b_input_ids, attention_mask=b_input_masks, token_type_ids=b_input_type_ids, start_positions=b_y_st, end_positions=b_y_end) loss = outputs[0] loss.backward() # Clip the norm of the gradients to 1.0. # This is to help prevent the "exploding gradients" problem. if self.clip_norm: torch.nn.utils.clip_grad_norm_(self.model.parameters(), self.clip_norm) self.optimizer.step() if self.lr_scheduler is not None: self.lr_scheduler.step() return {'loss': loss.item()}
[docs] def __call__(self, features: List[InputFeatures]) -> Tuple[List[int], List[int], List[float], List[float]]: """get predictions using features as input Args: features: batch of InputFeatures instances Returns: predictions: start, end positions, start, end logits positions """ input_ids = [f.input_ids for f in features] input_masks = [f.attention_mask for f in features] input_type_ids = [f.token_type_ids for f in features] b_input_ids =, dim=0).to(self.device) b_input_masks =, dim=0).to(self.device) b_input_type_ids =, dim=0).to(self.device) with torch.no_grad(): # Forward pass, calculate logit predictions outputs = self.model(input_ids=b_input_ids, attention_mask=b_input_masks, token_type_ids=b_input_type_ids) logits_st, logits_end = outputs[:2] bs = b_input_ids.size()[0] seq_len = b_input_ids.size()[-1] mask =[torch.ones(bs, 1, dtype=torch.int32), torch.zeros(bs, seq_len - 1, dtype=torch.int32)], dim=-1).to(self.device) logit_mask = b_input_type_ids + mask logits_st = softmax_mask(logits_st, logit_mask) logits_end = softmax_mask(logits_end, logit_mask) start_probs = torch.nn.functional.softmax(logits_st, dim=-1) end_probs = torch.nn.functional.softmax(logits_end, dim=-1) scores = torch.tensor(1) - start_probs[:, 0] * end_probs[:, 0] # ok outer = torch.matmul(start_probs.view(*start_probs.size(), 1), end_probs.view(end_probs.size()[0], 1, end_probs.size()[1])) outer_logits = torch.exp(logits_st.view(*logits_st.size(), 1) + logits_end.view( logits_end.size()[0], 1, logits_end.size()[1])) context_max_len = torch.max(torch.sum(b_input_type_ids, dim=1)).to(torch.int64) max_ans_length = torch.min(torch.tensor(20).to(self.device), context_max_len).to(torch.int64).item() outer = torch.triu(outer, diagonal=0) - torch.triu(outer, diagonal=outer.size()[1] - max_ans_length) outer_logits = torch.triu(outer_logits, diagonal=0) - torch.triu( outer_logits, diagonal=outer_logits.size()[1] - max_ans_length) start_pred = torch.argmax(torch.max(outer, dim=2)[0], dim=1) end_pred = torch.argmax(torch.max(outer, dim=1)[0], dim=1) logits = torch.max(torch.max(outer_logits, dim=2)[0], dim=1)[0] # Move logits and labels to CPU and to numpy arrays start_pred = start_pred.detach().cpu().numpy() end_pred = end_pred.detach().cpu().numpy() logits = logits.detach().cpu().numpy().tolist() scores = scores.detach().cpu().numpy().tolist() return start_pred, end_pred, logits, scores
@overrides def load(self, fname=None): if fname is not None: self.load_path = fname if self.pretrained_bert and not Path(self.pretrained_bert).is_file(): self.model = BertForQuestionAnswering.from_pretrained( self.pretrained_bert, output_attentions=False, output_hidden_states=False) elif self.bert_config_file and Path(self.bert_config_file).is_file(): self.bert_config = BertConfig.from_json_file(str(expand_path(self.bert_config_file))) if self.attention_probs_keep_prob is not None: self.bert_config.attention_probs_dropout_prob = 1.0 - self.attention_probs_keep_prob if self.hidden_keep_prob is not None: self.bert_config.hidden_dropout_prob = 1.0 - self.hidden_keep_prob self.model = BertForQuestionAnswering(config=self.bert_config) else: raise ConfigError("No pre-trained BERT model is given.") self.optimizer = getattr(torch.optim, self.optimizer_name)( self.model.parameters(), **self.optimizer_parameters) if self.lr_scheduler_name is not None: self.lr_scheduler = getattr(torch.optim.lr_scheduler, self.lr_scheduler_name)( self.optimizer, **self.lr_scheduler_parameters) if self.load_path:"Load path {self.load_path} is given.") if isinstance(self.load_path, Path) and not self.load_path.parent.is_dir(): raise ConfigError("Provided load path is incorrect!") weights_path = Path(self.load_path.resolve()) weights_path = weights_path.with_suffix(f".pth.tar") if weights_path.exists():"Load path {weights_path} exists.")"Initializing `{self.__class__.__name__}` from saved.") # now load the weights, optimizer from saved"Loading weights from {weights_path}.") checkpoint = torch.load(weights_path, map_location=self.device) self.model.load_state_dict(checkpoint["model_state_dict"]) self.optimizer.load_state_dict(checkpoint["optimizer_state_dict"]) self.epochs_done = checkpoint.get("epochs_done", 0) else:"Init from scratch. Load path {weights_path} does not exist.")
[docs]@register('torch_squad_bert_infer') class TorchBertSQuADInferModel(Component): """This model wraps BertSQuADModel to make predictions on longer than 512 tokens sequences. It splits context on chunks with `max_seq_length - 3 - len(question)` length, preserving sentences boundaries. It reassembles batches with chunks instead of full contexts to optimize performance, e.g.,: batch_size = 5 number_of_contexts == 2 number of first context chunks == 8 number of second context chunks == 2 we will create two batches with 5 chunks For each context the best answer is selected via logits or scores from BertSQuADModel. Args: squad_model_config: path to DeepPavlov BertSQuADModel config file vocab_file: path to Bert vocab file do_lower_case: set True if lowercasing is needed max_seq_length: max sequence length in subtokens, including [SEP] and [CLS] tokens batch_size: size of batch to use during inference lang: either `en` or `ru`, it is used to select sentence tokenizer """ def __init__(self, squad_model_config: str, vocab_file: str, do_lower_case: bool, max_seq_length: int = 512, batch_size: int = 10, lang: str = 'en', **kwargs) -> None: config = json.load(open(squad_model_config)) config['chainer']['pipe'][0]['max_seq_length'] = max_seq_length self.model = build_model(config) self.max_seq_length = max_seq_length if Path(vocab_file).is_file(): vocab_file = str(expand_path(vocab_file)) self.tokenizer = BertTokenizer(vocab_file=vocab_file, do_lower_case=do_lower_case) else: self.tokenizer = BertTokenizer.from_pretrained(vocab_file, do_lower_case=do_lower_case) self.batch_size = batch_size if lang == 'en': from nltk import sent_tokenize self.sent_tokenizer = sent_tokenize elif lang == 'ru': from ru_sent_tokenize import ru_sent_tokenize self.sent_tokenizer = ru_sent_tokenize else: raise RuntimeError('en and ru languages are supported only')
[docs] def __call__(self, contexts: List[str], questions: List[str], **kwargs) -> Tuple[List[str], List[int], List[float]]: """get predictions for given contexts and questions Args: contexts: batch of contexts questions: batch of questions Returns: predictions: answer, answer start position, logits or scores """ batch_indices = [] contexts_to_predict = [] questions_to_predict = [] predictions = {} for i, (context, question) in enumerate(zip(contexts, questions)): context_subtokens = self.tokenizer.tokenize(context) question_subtokens = self.tokenizer.tokenize(question) max_chunk_len = self.max_seq_length - len(question_subtokens) - 3 if 0 < max_chunk_len < len(context_subtokens): number_of_chunks = math.ceil(len(context_subtokens) / max_chunk_len) sentences = self.sent_tokenizer(context) for chunk in np.array_split(sentences, number_of_chunks): contexts_to_predict += [' '.join(chunk)] questions_to_predict += [question] batch_indices += [i] else: contexts_to_predict += [context] questions_to_predict += [question] batch_indices += [i] for j in range(0, len(contexts_to_predict), self.batch_size): c_batch = contexts_to_predict[j: j + self.batch_size] q_batch = questions_to_predict[j: j + self.batch_size] ind_batch = batch_indices[j: j + self.batch_size] a_batch, a_st_batch, logits_batch = self.model(c_batch, q_batch) for a, a_st, logits, ind in zip(a_batch, a_st_batch, logits_batch, ind_batch): if ind in predictions: predictions[ind] += [(a, a_st, logits)] else: predictions[ind] = [(a, a_st, logits)] answers, answer_starts, logits = [], [], [] for ind in sorted(predictions.keys()): prediction = predictions[ind] best_answer_ind = np.argmax([p[2] for p in prediction]) answers += [prediction[best_answer_ind][0]] answer_starts += [prediction[best_answer_ind][1]] logits += [prediction[best_answer_ind][2]] return answers, answer_starts, logits