initialize all entries given annotation json file

        Parameters:
        ----------
        anno_file: str
            annotation json file
        shuffle: bool
            whether to shuffle image list

def _load_all(self, anno_file, shuffle):
        """
        initialize all entries given annotation json file

        Parameters:
        ----------
        anno_file: str
            annotation json file
        shuffle: bool
            whether to shuffle image list
        """
        image_set_index = []
        labels = []
        coco = COCO(anno_file)
        img_ids = coco.getImgIds()
        # deal with class names
        cats = [cat['name'] for cat in coco.loadCats(coco.getCatIds())]
        class_to_coco_ind = dict(zip(cats, coco.getCatIds()))
        class_to_ind = dict(zip(self.classes, range(len(self.classes))))
        coco_ind_to_class_ind = dict([(class_to_coco_ind[cls], class_to_ind[cls])
                                     for cls in self.classes[0:]])
        for img_id in img_ids:
            # filename
            image_info = coco.loadImgs(img_id)[0]
            filename = image_info["file_name"]
            subdir = filename.split('_')[1]
            height = image_info["height"]
            width = image_info["width"]
            # label
            anno_ids = coco.getAnnIds(imgIds=img_id)
            annos = coco.loadAnns(anno_ids)
            label = []
            for anno in annos:
                cat_id = coco_ind_to_class_ind[anno['category_id']]
                bbox = anno["bbox"]
                assert len(bbox) == 4
                xmin = float(bbox[0]) / width
                ymin = float(bbox[1]) / height
                xmax = xmin + float(bbox[2]) / width
                ymax = ymin + float(bbox[3]) / height
                label.append([cat_id, xmin, ymin, xmax, ymax, 0])
            if label:
                labels.append(np.array(label))
                image_set_index.append(os.path.join(subdir, filename))

        if shuffle:
            import random
            indices = list(range(len(image_set_index)))
            random.shuffle(indices)
            image_set_index = [image_set_index[i] for i in indices]
            labels = [labels[i] for i in indices]
        # store the results
        self.image_set_index = image_set_index
        self.labels = labels