def apply(self, sample, context=None):
        """Filp the image and bounding box.
        Operators:
            1. Flip the image numpy.
            2. Transform the bboxes' x coordinates.
              (Must judge whether the coordinates are normalized!)
            3. Transform the segmentations' x coordinates.
              (Must judge whether the coordinates are normalized!)
        Output:
            sample: the image, bounding box and segmentation part
                    in sample are flipped.
        """
        if np.random.uniform(0, 1) < self.prob:
            im = sample['image']
            height, width = im.shape[:2]
            im = self.apply_image(im)
            if 'gt_bbox' in sample and len(sample['gt_bbox']) > 0:
                sample['gt_bbox'] = self.apply_bbox(sample['gt_bbox'], width)
            if 'gt_poly' in sample and len(sample['gt_poly']) > 0:
                sample['gt_poly'] = self.apply_segm(sample['gt_poly'], height,
                                                    width)
            if 'gt_keypoint' in sample and len(sample['gt_keypoint']) > 0:
                sample['gt_keypoint'] = self.apply_keypoint(
                    sample['gt_keypoint'], width)

            if 'semantic' in sample and sample['semantic']:
                sample['semantic'] = sample['semantic'][:, ::-1]

            if 'gt_segm' in sample and sample['gt_segm'].any():
                sample['gt_segm'] = sample['gt_segm'][:, :, ::-1]

            sample['flipped'] = True
            sample['image'] = im
        return sample
Filp the image and bounding box.
        Operators:
            1. Flip the image numpy.
            2. Transform the bboxes' x coordinates.
              (Must judge whether the coordinates are normalized!)
            3. Transform the segmentations' x coordinates.
              (Must judge whether the coordinates are normalized!)
        Output:
            sample: the image, bounding box and segmentation part
                    in sample are flipped.
        
ppdet/data/transform/operators.py