imagenet_dataset.py

#
# For licensing see accompanying LICENSE file.
# Copyright (C) 2019 Apple Inc. All Rights Reserved.
#
import torchvision.datasets as datasets
from PIL import Image


def pil_loader(path):
    # open path as file to avoid ResourceWarning (https://github.com/python-pillow/Pillow/issues/835)
    with open(path, 'rb') as f:
        img = Image.open(f)
        return img.convert('RGB')


def accimage_loader(path):
    import accimage
    try:
        return accimage.Image(path)
    except IOError:
        # fall back to PIL Image
        return pil_loader(path)


def default_loader(path):
    from torchvision import get_image_backend
    if get_image_backend() == 'accimage':
        return accimage_loader(path)
    else:
        return pil_loader(path)


class ImageFolderWithIdx(datasets.ImageFolder):
    """
    Extends ImageFolder dataset to yield index of element in dataset in addition to image and target label.

    Args:
        root (string): Root directory path.
        transform (callable, optional): A function/transform that  takes in an PIL image
            and returns a transformed version. E.g, ``transforms.RandomCrop``
        target_transform (callable, optional): A function/transform that takes in the
            target and transforms it.
        loader (callable, optional): A function to load an image given its path.

     Attributes:
        classes (list): List of the class names.
        class_to_idx (dict): Dict with items (class_name, class_index).
        imgs (list): List of (image path, class_index) tuples
    """
    def __init__(self,
                 root,
                 transform=None,
                 target_transform=None,
                 loader=default_loader):
        super(ImageFolderWithIdx, self).__init__(root=root,
                                                 transform=transform,
                                                 target_transform=target_transform,
                                                 loader=loader)

    def __getitem__(self, index):
        """
        Args:
            index (int): Index

        Returns:
            tuple: (sample, target, index) where index is the index of this sample in dataset.
        """
        sample, target = super().__getitem__(index)
        return sample, target, index