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| import torch | |
| from . import losses | |
| from ..utils.rewards import init_scorer, get_self_critical_reward | |
| class LossWrapper(torch.nn.Module): | |
| def __init__(self, model, opt): | |
| super(LossWrapper, self).__init__() | |
| self.opt = opt | |
| self.model = model | |
| if opt.label_smoothing > 0: | |
| self.crit = losses.LabelSmoothing(smoothing=opt.label_smoothing) | |
| else: | |
| self.crit = losses.LanguageModelCriterion() | |
| self.rl_crit = losses.RewardCriterion() | |
| self.struc_crit = losses.StructureLosses(opt) | |
| def forward(self, fc_feats, att_feats, labels, masks, att_masks, gts, gt_indices, | |
| sc_flag, struc_flag): | |
| opt = self.opt | |
| out = {} | |
| if struc_flag: | |
| if opt.structure_loss_weight < 1: | |
| lm_loss = self.crit(self.model(fc_feats, att_feats, labels[..., :-1], att_masks), labels[..., 1:], masks[..., 1:]) | |
| else: | |
| lm_loss = torch.tensor(0).type_as(fc_feats) | |
| if opt.structure_loss_weight > 0: | |
| gen_result, sample_logprobs = self.model(fc_feats, att_feats, att_masks, | |
| opt={'sample_method':opt.train_sample_method, | |
| 'beam_size':opt.train_beam_size, | |
| 'output_logsoftmax': opt.struc_use_logsoftmax or opt.structure_loss_type == 'softmax_margin'\ | |
| or not 'margin' in opt.structure_loss_type, | |
| 'sample_n': opt.train_sample_n}, | |
| mode='sample') | |
| gts = [gts[_] for _ in gt_indices.tolist()] | |
| struc_loss = self.struc_crit(sample_logprobs, gen_result, gts) | |
| else: | |
| struc_loss = {'loss': torch.tensor(0).type_as(fc_feats), | |
| 'reward': torch.tensor(0).type_as(fc_feats)} | |
| loss = (1-opt.structure_loss_weight) * lm_loss + opt.structure_loss_weight * struc_loss['loss'] | |
| out['lm_loss'] = lm_loss | |
| out['struc_loss'] = struc_loss['loss'] | |
| out['reward'] = struc_loss['reward'] | |
| elif not sc_flag: | |
| loss = self.crit(self.model(fc_feats, att_feats, labels[..., :-1], att_masks), labels[..., 1:], masks[..., 1:]) | |
| else: | |
| self.model.eval() | |
| with torch.no_grad(): | |
| greedy_res, _ = self.model(fc_feats, att_feats, att_masks, | |
| mode='sample', | |
| opt={'sample_method': opt.sc_sample_method, | |
| 'beam_size': opt.sc_beam_size}) | |
| self.model.train() | |
| gen_result, sample_logprobs = self.model(fc_feats, att_feats, att_masks, | |
| opt={'sample_method':opt.train_sample_method, | |
| 'beam_size':opt.train_beam_size, | |
| 'sample_n': opt.train_sample_n}, | |
| mode='sample') | |
| gts = [gts[_] for _ in gt_indices.tolist()] | |
| reward = get_self_critical_reward(greedy_res, gts, gen_result, self.opt) | |
| reward = torch.from_numpy(reward).to(sample_logprobs) | |
| loss = self.rl_crit(sample_logprobs, gen_result.data, reward) | |
| out['reward'] = reward[:,0].mean() | |
| out['loss'] = loss | |
| return out | |