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104 lines
4.1 KiB
104 lines
4.1 KiB
5 months ago
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from os.path import join
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from pathlib import Path
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from typing import Any, Callable, List, Optional, Tuple, Union
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from PIL import Image
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from .utils import check_integrity, download_and_extract_archive, list_dir, list_files
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from .vision import VisionDataset
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class Omniglot(VisionDataset):
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"""`Omniglot <https://github.com/brendenlake/omniglot>`_ Dataset.
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Args:
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root (str or ``pathlib.Path``): Root directory of dataset where directory
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``omniglot-py`` exists.
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background (bool, optional): If True, creates dataset from the "background" set, otherwise
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creates from the "evaluation" set. This terminology is defined by the authors.
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transform (callable, optional): A function/transform that takes in a PIL image
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and returns a transformed version. E.g, ``transforms.RandomCrop``
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target_transform (callable, optional): A function/transform that takes in the
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target and transforms it.
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download (bool, optional): If true, downloads the dataset zip files from the internet and
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puts it in root directory. If the zip files are already downloaded, they are not
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downloaded again.
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"""
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folder = "omniglot-py"
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download_url_prefix = "https://raw.githubusercontent.com/brendenlake/omniglot/master/python"
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zips_md5 = {
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"images_background": "68d2efa1b9178cc56df9314c21c6e718",
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"images_evaluation": "6b91aef0f799c5bb55b94e3f2daec811",
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}
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def __init__(
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self,
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root: Union[str, Path],
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background: bool = True,
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transform: Optional[Callable] = None,
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target_transform: Optional[Callable] = None,
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download: bool = False,
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) -> None:
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super().__init__(join(root, self.folder), transform=transform, target_transform=target_transform)
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self.background = background
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if download:
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self.download()
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if not self._check_integrity():
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raise RuntimeError("Dataset not found or corrupted. You can use download=True to download it")
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self.target_folder = join(self.root, self._get_target_folder())
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self._alphabets = list_dir(self.target_folder)
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self._characters: List[str] = sum(
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([join(a, c) for c in list_dir(join(self.target_folder, a))] for a in self._alphabets), []
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)
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self._character_images = [
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[(image, idx) for image in list_files(join(self.target_folder, character), ".png")]
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for idx, character in enumerate(self._characters)
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]
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self._flat_character_images: List[Tuple[str, int]] = sum(self._character_images, [])
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def __len__(self) -> int:
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return len(self._flat_character_images)
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def __getitem__(self, index: int) -> Tuple[Any, Any]:
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"""
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Args:
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index (int): Index
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Returns:
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tuple: (image, target) where target is index of the target character class.
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"""
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image_name, character_class = self._flat_character_images[index]
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image_path = join(self.target_folder, self._characters[character_class], image_name)
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image = Image.open(image_path, mode="r").convert("L")
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if self.transform:
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image = self.transform(image)
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if self.target_transform:
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character_class = self.target_transform(character_class)
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return image, character_class
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def _check_integrity(self) -> bool:
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zip_filename = self._get_target_folder()
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if not check_integrity(join(self.root, zip_filename + ".zip"), self.zips_md5[zip_filename]):
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return False
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return True
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def download(self) -> None:
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if self._check_integrity():
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print("Files already downloaded and verified")
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return
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filename = self._get_target_folder()
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zip_filename = filename + ".zip"
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url = self.download_url_prefix + "/" + zip_filename
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download_and_extract_archive(url, self.root, filename=zip_filename, md5=self.zips_md5[filename])
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def _get_target_folder(self) -> str:
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return "images_background" if self.background else "images_evaluation"
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