def __init__(self, image_set, root_path, dataset_path, result_path=None):
        """
        fill basic information to initialize imdb
        :param image_set: leftImg8bit_train, etc
        :param root_path: 'selective_search_data' and 'cache'
        :param dataset_path: data and results
        :return: imdb object
        """
        image_set_main_folder, image_set_sub_folder= image_set.split('_', 1)
        super(CityScape, self).__init__('cityscape', image_set, root_path, dataset_path, result_path)  # set self.name

        self.image_set_main_folder = image_set_main_folder
        self.image_set_sub_folder = image_set_sub_folder
        self.root_path = root_path
        self.data_path = dataset_path
        self.num_classes = 19
        self.image_set_index = self.load_image_set_index()
        self.num_images = len(self.image_set_index)
        print 'num_images', self.num_images

        self.config = {'comp_id': 'comp4',
                       'use_diff': False,
                       'min_size': 2}

        fill basic information to initialize imdb
        :param image_set: leftImg8bit_train, etc
        :param root_path: 'selective_search_data' and 'cache'
        :param dataset_path: data and results
        :return: imdb object
        
lib/dataset/cityscape.py