text: import os
  from typing import Optional
  from .imagelist import ImageList
  from ._util import download as download_data, check_exits
  
  
  class CUB200(ImageList):
      """`Caltech-UCSD Birds-200-2011 <http://www.vision.caltech.edu/visipedia/CUB-200-2011.html>`_ Dataset.
  
      Args:
          root (str): Root directory of dataset
          split (str, optional): The dataset split, supports ``train``, or ``test``.
          sample_rate (int): The sampling rates to sample random ``training`` images for each category.
              Choices include 100, 50, 30, 15. Default: 100.
          download (bool, optional): If true, downloads the dataset from the internet and puts it \
              in root directory. If dataset is already downloaded, it is not downloaded again.
          transform (callable, optional): A function/transform that  takes in an PIL image and returns a \
              transformed version. E.g, :class:`torchvision.transforms.RandomCrop`.
          target_transform (callable, optional): A function/transform that takes in the target and transforms it.
  
      .. note:: In `root`, there will exist following files after downloading.
          ::
              train/
              test/
              image_list/
                  train_100.txt
                  train_50.txt
                  train_30.txt
                  train_15.txt
                  test.txt
      """
      download_list = [
          ("image_list", "image_list.zip", "https://cloud.tsinghua.edu.cn/f/fa398a321b094a24a347/?dl=1"),
          ("train", "train.tgz", "https://cloud.tsinghua.edu.cn/f/521ba92bafc04ee69c20/?dl=1"),
          ("test", "test.tgz", "https://cloud.tsinghua.edu.cn/f/cc7ef72081e64bc7a218/?dl=1"),
      ]
      image_list = {
          "train": "image_list/train_100.txt",
          "train100": "image_list/train_100.txt",
          "train50": "image_list/train_50.txt",
          "train30": "image_list/train_30.txt",
          "train15": "image_list/train_15.txt",
          "test": "image_list/test.txt",
          "test100": "image_list/test.txt",
      }
      CLASSES = ['001.Black_footed_Albatross', '002.Laysan_Albatross', '003.Sooty_Albatross', '004.Groove_billed_Ani', '005.Crested_Auklet', '006.Least_Auklet', '007.Parakeet_Auklet', '008.Rhinoceros_Auklet', '009.Brewer_Blackbird', '010.Red_winged_Blackbird', '011.Rusty_Blackbird', '012.Yellow_headed_Blackbird', '013.Bobolink', '014.Indigo_Bunting', '015.Lazuli_Bunting', '016.Painted_Bunting', '017.Cardinal', '018.Spotted_Catbird', '019.Gray_Catbird', '020.Yellow_breasted_Chat', '021.Eastern_Towhee', '022.Chuck_will_Widow', '023.Brandt_Cormorant', '024.Red_faced_Cormorant', '025.Pelagic_Cormorant', '026.Bronzed_Cowbird', '027.Shiny_Cowbird', '028.Brown_Creeper', '029.American_Crow', '030.Fish_Crow', '031.Black_billed_Cuckoo', '032.Mangrove_Cuckoo', '033.Yellow_billed_Cuckoo', '034.Gray_crowned_Rosy_Finch', '035.Purple_Finch', '036.Northern_Flicker', '037.Acadian_Flycatcher', '038.Great_Crested_Flycatcher', '039.Least_Flycatcher', '040.Olive_sided_Flycatcher', '041.Scissor_tailed_Flycatcher', '042.Vermilion_Flycatcher', '043.Yellow_bellied_Flycatcher', '044.Frigatebird', '045.Northern_Fulmar', '046.Gadwall', '047.American_Goldfinch', '048.European_Goldfinch', '049.Boat_tailed_Grackle', '050.Eared_Grebe',
                 '051.Horned_Grebe', '052.Pied_billed_Grebe', '053.Western_Grebe', '054.Blue_Grosbeak', '055.Evening_Grosbeak', '056.Pine_Grosbeak', '057.Rose_breasted_Grosbeak', '058.Pigeon_Guillemot', '059.California_Gull', '060.Glaucous_winged_Gull', '061.Heermann_Gull', '062.Herring_Gull', '063.Ivory_Gull', '064.Ring_billed_Gull', '065.Slaty_backed_Gull', '066.Western_Gull', '067.Anna_Hummingbird', '068.Ruby_throated_Hummingbird', '069.Rufous_Hummingbird', '070.Green_Violetear', '071.Long_tailed_Jaeger', '072.Pomarine_Jaeger', '073.Blue_Jay', '074.Florida_Jay', '075.Green_Jay', '076.Dark_eyed_Junco', '077.Tropical_Kingbird', '078.Gray_Kingbird', '079.Belted_Kingfisher', '080.Green_Kingfisher', '081.Pied_Kingfisher', '082.Ringed_Kingfisher', '083.White_breasted_Kingfisher', '084.Red_legged_Kittiwake', '085.Horned_Lark', '086.Pacific_Loon', '087.Mallard', '088.Western_Meadowlark', '089.Hooded_Merganser', '090.Red_breasted_Merganser', '091.Mockingbird', '092.Nighthawk', '093.Clark_Nutcracker', '094.White_breasted_Nuthatch', '095.Baltimore_Oriole', '096.Hooded_Oriole', '097.Orchard_Oriole', '098.Scott_Oriole', '099.Ovenbird', '100.Brown_Pelican',
                 '101.White_Pelican', '102.Western_Wood_Pewee', '103.Sayornis', '104.American_Pipit', '105.Whip_poor_Will', '106.Horned_Puffin', '107.Common_Raven', '108.White_necked_Raven', '109.American_Redstart', '110.Geococcyx', '111.Loggerhead_Shrike', '112.Great_Grey_Shrike', '113.Baird_Sparrow', '114.Black_throated_Sparrow', '115.Brewer_Sparrow', '116.Chipping_Sparrow', '117.Clay_colored_Sparrow', '118.House_Sparrow', '119.Field_Sparrow', '120.Fox_Sparrow', '121.Grasshopper_Sparrow', '122.Harris_Sparrow', '123.Henslow_Sparrow', '124.Le_Conte_Sparrow', '125.Lincoln_Sparrow', '126.Nelson_Sharp_tailed_Sparrow', '127.Savannah_Sparrow', '128.Seaside_Sparrow', '129.Song_Sparrow', '130.Tree_Sparrow', '131.Vesper_Sparrow', '132.White_crowned_Sparrow', '133.White_throated_Sparrow', '134.Cape_Glossy_Starling', '135.Bank_Swallow', '136.Barn_Swallow', '137.Cliff_Swallow', '138.Tree_Swallow', '139.Scarlet_Tanager', '140.Summer_Tanager', '141.Artic_Tern', '142.Black_Tern', '143.Caspian_Tern', '144.Common_Tern', '145.Elegant_Tern', '146.Forsters_Tern', '147.Least_Tern', '148.Green_tailed_Towhee', '149.Brown_Thrasher', '150.Sage_Thrasher',
                 '151.Black_capped_Vireo', '152.Blue_headed_Vireo', '153.Philadelphia_Vireo', '154.Red_eyed_Vireo', '155.Warbling_Vireo', '156.White_eyed_Vireo', '157.Yellow_throated_Vireo', '158.Bay_breasted_Warbler', '159.Black_and_white_Warbler', '160.Black_throated_Blue_Warbler', '161.Blue_winged_Warbler', '162.Canada_Warbler', '163.Cape_May_Warbler', '164.Cerulean_Warbler', '165.Chestnut_sided_Warbler', '166.Golden_winged_Warbler', '167.Hooded_Warbler', '168.Kentucky_Warbler', '169.Magnolia_Warbler', '170.Mourning_Warbler', '171.Myrtle_Warbler', '172.Nashville_Warbler', '173.Orange_crowned_Warbler', '174.Palm_Warbler', '175.Pine_Warbler', '176.Prairie_Warbler', '177.Prothonotary_Warbler', '178.Swainson_Warbler', '179.Tennessee_Warbler', '180.Wilson_Warbler', '181.Worm_eating_Warbler', '182.Yellow_Warbler', '183.Northern_Waterthrush', '184.Louisiana_Waterthrush', '185.Bohemian_Waxwing', '186.Cedar_Waxwing', '187.American_Three_toed_Woodpecker', '188.Pileated_Woodpecker', '189.Red_bellied_Woodpecker', '190.Red_cockaded_Woodpecker', '191.Red_headed_Woodpecker', '192.Downy_Woodpecker', '193.Bewick_Wren', '194.Cactus_Wren', '195.Carolina_Wren', '196.House_Wren', '197.Marsh_Wren', '198.Rock_Wren', '199.Winter_Wren', '200.Common_Yellowthroat']
  
      def __init__(self, root: str, split: str, sample_rate: Optional[int] =100, download: Optional[bool] = False, **kwargs):
  
          if split == 'train':
              list_name = 'train' + str(sample_rate)
              assert list_name in self.image_list
              data_list_file = os.path.join(root, self.image_list[list_name])
          else:
              data_list_file = os.path.join(root, self.image_list['test'])
  
          if download:
              list(map(lambda args: download_data(root, *args), self.download_list))
          else:
              list(map(lambda file_name, _: check_exits(root, file_name), self.download_list))
  
          super(CUB200, self).__init__(root, CUB200.CLASSES, data_list_file=data_list_file, **kwargs)
  