def __init__(
        self,
        data_dir=None,
        json_file="train_half.json",
        name="train",
        img_size=(608, 1088),
        preproc=None,
    ):
        """
        COCO dataset initialization. Annotation data are read into memory by COCO API.
        Args:
            data_dir (str): dataset root directory
            json_file (str): COCO json file name
            name (str): COCO data name (e.g. 'train2017' or 'val2017')
            img_size (int): target image size after pre-processing
            preproc: data augmentation strategy
        """
        super().__init__(img_size)
        if data_dir is None:
            data_dir = os.path.join(get_yolox_datadir(), "mot")
        self.data_dir = data_dir
        self.json_file = json_file

        self.coco = COCO(os.path.join(self.data_dir, "annotations", self.json_file))
        self.ids = self.coco.getImgIds()
        self.class_ids = sorted(self.coco.getCatIds())
        cats = self.coco.loadCats(self.coco.getCatIds())
        self._classes = tuple([c["name"] for c in cats])
        self.annotations = self._load_coco_annotations()
        self.name = name
        self.img_size = img_size
        self.preproc = preproc

        COCO dataset initialization. Annotation data are read into memory by COCO API.
        Args:
            data_dir (str): dataset root directory
            json_file (str): COCO json file name
            name (str): COCO data name (e.g. 'train2017' or 'val2017')
            img_size (int): target image size after pre-processing
            preproc: data augmentation strategy
        
yolox/data/datasets/mot.py