@ptrblck
what I have is that the data is read from a folder like that
class ImageFolder(data.Dataset):

    def __init__(self, root, transform=None, return_paths=False,
                 loader=default_loader):
        imgs = sorted(make_dataset(root))
        if len(imgs) == 0:
            raise(RuntimeError("Found 0 images in: " + root + "\n"
                               "Supported image extensions are: " +
                               ",".join(IMG_EXTENSIONS)))

        self.root = root
        self.imgs = imgs
        self.transform = transform
        self.return_paths = return_paths
        self.loader = loader

    def __getitem__(self, index):
        path = self.imgs[index]
        img = self.loader(path)
        if self.transform is not None:
            img = self.transform(img)
        if self.return_paths:
            return img, path
        else:
            return img

    def __len__(self):
        return len(self.imgs)

def get_data_loader_folder(input_folder, batch_size, train, new_size=None,
                           height=256, width=256, num_workers=4, crop=True):
    transform_list = [transforms.ToTensor(),
                      transforms.Normalize((0.5, 0.5, 0.5),
                                           (0.5, 0.5, 0.5))]
    transform_list = [transforms.RandomCrop((height, width))] + transform_list if crop else transform_list
    transform_list = [transforms.Resize((256, 256))] + transform_list if new_size is not None else transform_list
    transform_list = [transforms.RandomHorizontalFlip()] + transform_list if train else transform_list
    transform = transforms.Compose(transform_list)
    dataset = ImageFolder(input_folder, transform=transform)
    loader = DataLoader(dataset=dataset, batch_size=batch_size, shuffle=train, drop_last=True, num_workers=num_workers)
    return loader


So where exactly can I put the sampler in this case ?
Also another question, I believe that the output in this case for each batch would be a pair, right ? I think this will already cause memory error in my case, they don’t exactly have to be pairs in one batch, what I want is that they are sorted in the manner of shuffled pairs, and concerning the invalid indices, I already have a threshold calculation, which tells me if the current frame(image) is from the same sequence of the previous image or not, or even I can do it every 2nd batch … this can be easily doable I think so