Load a subset of the COCO dataset. dataset_dir: The root directory of the COCO dataset. subset: What to load (train, val, minival, val35k) class_ids: If provided, only loads images that have the given classes. class_map: TODO: Not implemented yet. Supports maping clas
(self, dataset_dir, subset, class_ids=None,
class_map=None, return_coco=False)