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Source code for mmcls.models.heads.conformer_head

# Copyright (c) OpenMMLab. All rights reserved.
import torch.nn as nn
import torch.nn.functional as F
from mmcv.cnn.utils.weight_init import trunc_normal_

from ..builder import HEADS
from .cls_head import ClsHead


[docs]@HEADS.register_module() class ConformerHead(ClsHead): """Linear classifier head. Args: num_classes (int): Number of categories excluding the background category. in_channels (int): Number of channels in the input feature map. init_cfg (dict | optional): The extra init config of layers. Defaults to use ``dict(type='Normal', layer='Linear', std=0.01)``. """ def __init__( self, num_classes, in_channels, # [conv_dim, trans_dim] init_cfg=dict(type='Normal', layer='Linear', std=0.01), *args, **kwargs): super(ConformerHead, self).__init__(init_cfg=None, *args, **kwargs) self.in_channels = in_channels self.num_classes = num_classes self.init_cfg = init_cfg if self.num_classes <= 0: raise ValueError( f'num_classes={num_classes} must be a positive integer') self.conv_cls_head = nn.Linear(self.in_channels[0], num_classes) self.trans_cls_head = nn.Linear(self.in_channels[1], num_classes) def _init_weights(self, m): if isinstance(m, nn.Linear): trunc_normal_(m.weight, std=.02) if isinstance(m, nn.Linear) and m.bias is not None: nn.init.constant_(m.bias, 0)
[docs] def init_weights(self): super(ConformerHead, self).init_weights() if (isinstance(self.init_cfg, dict) and self.init_cfg['type'] == 'Pretrained'): # Suppress default init if use pretrained model. return else: self.apply(self._init_weights)
def pre_logits(self, x): if isinstance(x, tuple): x = x[-1] return x
[docs] def simple_test(self, x, softmax=True, post_process=True): """Inference without augmentation. Args: x (tuple[tuple[tensor, tensor]]): The input features. Multi-stage inputs are acceptable but only the last stage will be used to classify. Every item should be a tuple which includes convluation features and transformer features. The shape of them should be ``(num_samples, in_channels[0])`` and ``(num_samples, in_channels[1])``. softmax (bool): Whether to softmax the classification score. post_process (bool): Whether to do post processing the inference results. It will convert the output to a list. Returns: Tensor | list: The inference results. - If no post processing, the output is a tensor with shape ``(num_samples, num_classes)``. - If post processing, the output is a multi-dimentional list of float and the dimensions are ``(num_samples, num_classes)``. """ x = self.pre_logits(x) # There are two outputs in the Conformer model assert len(x) == 2 conv_cls_score = self.conv_cls_head(x[0]) tran_cls_score = self.trans_cls_head(x[1]) if softmax: cls_score = conv_cls_score + tran_cls_score pred = ( F.softmax(cls_score, dim=1) if cls_score is not None else None) if post_process: pred = self.post_process(pred) else: pred = [conv_cls_score, tran_cls_score] if post_process: pred = list(map(self.post_process, pred)) return pred
def forward_train(self, x, gt_label): x = self.pre_logits(x) assert isinstance(x, list) and len(x) == 2, \ 'There should be two outputs in the Conformer model' conv_cls_score = self.conv_cls_head(x[0]) tran_cls_score = self.trans_cls_head(x[1]) losses = self.loss([conv_cls_score, tran_cls_score], gt_label) return losses def loss(self, cls_score, gt_label): num_samples = len(cls_score[0]) losses = dict() # compute loss loss = sum([ self.compute_loss(score, gt_label, avg_factor=num_samples) / len(cls_score) for score in cls_score ]) if self.cal_acc: # compute accuracy acc = self.compute_accuracy(cls_score[0] + cls_score[1], gt_label) assert len(acc) == len(self.topk) losses['accuracy'] = { f'top-{k}': a for k, a in zip(self.topk, acc) } losses['loss'] = loss return losses
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