58 lines
1.6 KiB
Python
58 lines
1.6 KiB
Python
# Copyright (c) OpenMMLab. All rights reserved.
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from abc import ABCMeta, abstractmethod
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import numpy as np
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import torch
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import torch.nn.functional as F
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from .builder import AUGMENT
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class BaseMixupLayer(object, metaclass=ABCMeta):
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"""Base class for MixupLayer.
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Args:
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alpha (float): Parameters for Beta distribution.
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num_classes (int): The number of classes.
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prob (float): MixUp probability. It should be in range [0, 1].
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Default to 1.0
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"""
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def __init__(self, alpha, num_classes, prob=1.0):
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super(BaseMixupLayer, self).__init__()
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assert isinstance(alpha, float) and alpha > 0
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assert isinstance(num_classes, int)
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assert isinstance(prob, float) and 0.0 <= prob <= 1.0
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self.alpha = alpha
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self.num_classes = num_classes
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self.prob = prob
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@abstractmethod
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def mixup(self, imgs, gt_label):
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pass
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@AUGMENT.register_module(name='BatchMixup')
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class BatchMixupLayer(BaseMixupLayer):
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"""Mixup layer for batch mixup."""
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def __init__(self, *args, **kwargs):
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super(BatchMixupLayer, self).__init__(*args, **kwargs)
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def mixup(self, img, gt_label):
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one_hot_gt_label = F.one_hot(gt_label, num_classes=self.num_classes)
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lam = np.random.beta(self.alpha, self.alpha)
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batch_size = img.size(0)
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index = torch.randperm(batch_size)
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mixed_img = lam * img + (1 - lam) * img[index, :]
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mixed_gt_label = lam * one_hot_gt_label + (
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1 - lam) * one_hot_gt_label[index, :]
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return mixed_img, mixed_gt_label
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def __call__(self, img, gt_label):
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return self.mixup(img, gt_label)
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