def __init__(self, name, image_set, root_path, dataset_path, result_path=None):
        """
        basic information about an image database
        :param name: name of image database will be used for any output
        :param root_path: root path store cache and proposal data
        :param dataset_path: dataset path store images and image lists
        """
        self.name = name + '_' + image_set
        self.image_set = image_set
        self.root_path = root_path
        self.data_path = dataset_path
        self._result_path = result_path

        # abstract attributes
        self.classes = []
        self.num_classes = 0
        self.image_set_index = []
        self.num_images = 0

        self.config = {}

        basic information about an image database
        :param name: name of image database will be used for any output
        :param root_path: root path store cache and proposal data
        :param dataset_path: dataset path store images and image lists
        
lib/dataset/imdb.py