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Source code for mmcls.models.heads.multi_label_linear_head

# Copyright (c) OpenMMLab. All rights reserved.
import torch
import torch.nn as nn

from ..builder import HEADS
from .multi_label_head import MultiLabelClsHead

[docs]@HEADS.register_module() class MultiLabelLinearClsHead(MultiLabelClsHead): """Linear classification head for multilabel task. Args: num_classes (int): Number of categories. in_channels (int): Number of channels in the input feature map. loss (dict): Config of classification loss. 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, loss=dict( type='CrossEntropyLoss', use_sigmoid=True, reduction='mean', loss_weight=1.0), init_cfg=dict(type='Normal', layer='Linear', std=0.01)): super(MultiLabelLinearClsHead, self).__init__( loss=loss, init_cfg=init_cfg) if num_classes <= 0: raise ValueError( f'num_classes={num_classes} must be a positive integer') self.in_channels = in_channels self.num_classes = num_classes self.fc = nn.Linear(self.in_channels, self.num_classes) def pre_logits(self, x): if isinstance(x, tuple): x = x[-1] return x def forward_train(self, x, gt_label, **kwargs): x = self.pre_logits(x) gt_label = gt_label.type_as(x) cls_score = self.fc(x) losses = self.loss(cls_score, gt_label, **kwargs) return losses
[docs] def simple_test(self, x, sigmoid=True, post_process=True): """Inference without augmentation. Args: x (tuple[Tensor]): The input features. Multi-stage inputs are acceptable but only the last stage will be used to classify. The shape of every item should be ``(num_samples, in_channels)``. sigmoid (bool): Whether to sigmoid 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) cls_score = self.fc(x) if sigmoid: pred = torch.sigmoid(cls_score) if cls_score is not None else None else: pred = cls_score if post_process: return self.post_process(pred) else: return pred
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