In train.py, the "dataloader" does not match the tag data of the "targets"!

[xlnn]

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YOLOv5 Component

Training

Bug

Hello,I have a problem,as follows: The dataloader does not match the tag data of the targets!

This is targets:

This is dataloader:

In train.py. The target data for targets must come from the data in the dataloader, but why can't I find the data for targets in the dataloader? Any idea why, thanks!

Environment

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Minimal Reproducible Example

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Additional

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Are you willing to submit a PR?

• [X] Yes I'd like to help by submitting a PR!

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[glenn-jocher]

@xlnn hi there! Thank you for reporting this issue with the dataloader and the targets in train.py. I appreciate your effort in providing the relevant images for better understanding.

In YOLOv5, the target data for the targets should indeed come from the data in the dataloader. From the screenshots you provided, it seems that the targets object in your code does not have the expected tag data.

To help you better, I would need more information such as the code snippet where you initialize the dataloader and the targets object. Additionally, it would be helpful if you could include some example code on how you are using the dataloader and the targets.

With this additional information, I can assist you further in troubleshooting the issue. Thank you for your willingness to submit a pull request. Your contributions are valuable to the YOLOv5 community!

[xlnn]

@xlnn hi there! Thank you for reporting this issue with the dataloader and the targets in train.py. I appreciate your effort in providing the relevant images for better understanding.

In YOLOv5, the target data for the targets should indeed come from the data in the dataloader. From the screenshots you provided, it seems that the targets object in your code does not have the expected tag data.

To help you better, I would need more information such as the code snippet where you initialize the dataloader and the targets object. Additionally, it would be helpful if you could include some example code on how you are using the dataloader and the targets.

With this additional information, I can assist you further in troubleshooting the issue. Thank you for your willingness to submit a pull request. Your contributions are valuable to the YOLOv5 community!

Thank you!This is my "create_dataloader" function as follows:

    # Trainloader
    dataloader, dataset = create_dataloader(train_path, imgsz, batch_size, gs, opt,
                                            hyp=hyp, augment=True, cache=opt.cache_images, rect=opt.rect, rank=rank,
                                            world_size=opt.world_size, workers=opt.workers,
                                            image_weights=opt.image_weights, quad=opt.quad, prefix=colorstr('train: '))

def create_dataloader(path, imgsz, batch_size, stride, opt, hyp=None, augment=False, cache=False, pad=0.0, rect=False,
                      rank=-1, world_size=1, workers=8, image_weights=False, quad=False, prefix=''):
    # Make sure only the first process in DDP process the dataset first, and the following others can use the cache
    with torch_distributed_zero_first(rank):
        dataset = LoadImagesAndLabels(path, imgsz, batch_size,
                                      augment=augment,  # augment images
                                      hyp=hyp,  # augmentation hyperparameters
                                      rect=rect,  # rectangular training
                                      cache_images=cache,
                                      single_cls=opt.single_cls,
                                      stride=int(stride),
                                      pad=pad,
                                      image_weights=image_weights,
                                      prefix=prefix)

    batch_size = min(batch_size, len(dataset))
    nw = min([os.cpu_count() // world_size, batch_size if batch_size > 1 else 0, workers])  # number of workers
    sampler = torch.utils.data.distributed.DistributedSampler(dataset) if rank != -1 else None
    loader = torch.utils.data.DataLoader if image_weights else InfiniteDataLoader
    # Use torch.utils.data.DataLoader() if dataset.properties will update during training else InfiniteDataLoader()
    dataloader = loader(dataset,
                        batch_size=batch_size,
                        num_workers=nw,
                        sampler=sampler,
                        pin_memory=True,
                        collate_fn=LoadImagesAndLabels.collate_fn4 if quad else LoadImagesAndLabels.collate_fn)
    return dataloader, dataset

class LoadImagesAndLabels(Dataset):  # for training/testing
    def __init__(self, path, img_size=640, batch_size=16, augment=False, hyp=None, rect=False, image_weights=False,
                 cache_images=False, single_cls=False, stride=32, pad=0.0, prefix=''):
        self.img_size = img_size
        self.augment = augment
        self.hyp = hyp
        self.image_weights = image_weights
        self.rect = False if image_weights else rect
        self.mosaic = self.augment and not self.rect  # load 4 images at a time into a mosaic (only during training)
        self.mosaic_border = [-img_size // 2, -img_size // 2]
        self.stride = stride
        self.path = path        
        #self.albumentations = Albumentations() if augment else None

        try:
            f = []  # image files
            for p in path if isinstance(path, list) else [path]:
                p = Path(p)  # os-agnostic
                if p.is_dir():  # dir
                    f += glob.glob(str(p / '**' / '*.*'), recursive=True)
                    # f = list(p.rglob('**/*.*'))  # pathlib
                elif p.is_file():  # file
                    with open(p, 'r') as t:
                        t = t.read().strip().splitlines()
                        parent = str(p.parent) + os.sep
                        f += [x.replace('./', parent) if x.startswith('./') else x for x in t]  # local to global path
                        # f += [p.parent / x.lstrip(os.sep) for x in t]  # local to global path (pathlib)
                else:
                    raise Exception(f'{prefix}{p} does not exist')
            self.img_files = sorted([x.replace('/', os.sep) for x in f if x.split('.')[-1].lower() in img_formats])
            # self.img_files = sorted([x for x in f if x.suffix[1:].lower() in img_formats])  # pathlib
            assert self.img_files, f'{prefix}No images found'
        except Exception as e:
            raise Exception(f'{prefix}Error loading data from {path}: {e}\nSee {help_url}')

        # Check cache
        self.label_files = img2label_paths(self.img_files)  # labels
        cache_path = (p if p.is_file() else Path(self.label_files[0]).parent).with_suffix('.cache')  # cached labels
        if cache_path.is_file():
            cache, exists = torch.load(cache_path), True  # load
            #if cache['hash'] != get_hash(self.label_files + self.img_files) or 'version' not in cache:  # changed
            #    cache, exists = self.cache_labels(cache_path, prefix), False  # re-cache
        else:
            cache, exists = self.cache_labels(cache_path, prefix), False  # cache

        # Display cache
        nf, nm, ne, nc, n = cache.pop('results')  # found, missing, empty, corrupted, total
        if exists:
            d = f"Scanning '{cache_path}' images and labels... {nf} found, {nm} missing, {ne} empty, {nc} corrupted"
            tqdm(None, desc=prefix + d, total=n, initial=n)  # display cache results
        assert nf > 0 or not augment, f'{prefix}No labels in {cache_path}. Can not train without labels. See {help_url}'

        # Read cache
        cache.pop('hash')  # remove hash
        cache.pop('version')  # remove version
        labels, shapes, self.segments = zip(*cache.values())
        self.labels = list(labels)
        self.shapes = np.array(shapes, dtype=np.float64)
        self.img_files = list(cache.keys())  # update
        self.label_files = img2label_paths(cache.keys())  # update
        if single_cls:
            for x in self.labels:
                x[:, 0] = 0

        n = len(shapes)  # number of images
        bi = np.floor(np.arange(n) / batch_size).astype(int)  # batch index
        nb = bi[-1] + 1  # number of batches
        self.batch = bi  # batch index of image
        self.n = n
        self.indices = range(n)

        # Rectangular Training
        if self.rect:
            # Sort by aspect ratio
            s = self.shapes  # wh
            ar = s[:, 1] / s[:, 0]  # aspect ratio
            irect = ar.argsort()
            self.img_files = [self.img_files[i] for i in irect]
            self.label_files = [self.label_files[i] for i in irect]
            self.labels = [self.labels[i] for i in irect]
            self.shapes = s[irect]  # wh
            ar = ar[irect]

            # Set training image shapes
            shapes = [[1, 1]] * nb
            for i in range(nb):
                ari = ar[bi == i]
                mini, maxi = ari.min(), ari.max()
                if maxi < 1:
                    shapes[i] = [maxi, 1]
                elif mini > 1:
                    shapes[i] = [1, 1 / mini]

            self.batch_shapes = np.ceil(np.array(shapes) * img_size / stride + pad).astype(int) * stride

        # Cache images into memory for faster training (WARNING: large datasets may exceed system RAM)
        self.imgs = [None] * n
        if cache_images:
            if cache_images == 'disk':
                self.im_cache_dir = Path(Path(self.img_files[0]).parent.as_posix() + '_npy')
                self.img_npy = [self.im_cache_dir / Path(f).with_suffix('.npy').name for f in self.img_files]
                self.im_cache_dir.mkdir(parents=True, exist_ok=True)
            gb = 0  # Gigabytes of cached images
            self.img_hw0, self.img_hw = [None] * n, [None] * n
            results = ThreadPool(8).imap(lambda x: load_image(*x), zip(repeat(self), range(n)))
            pbar = tqdm(enumerate(results), total=n)
            for i, x in pbar:
                if cache_images == 'disk':
                    if not self.img_npy[i].exists():
                        np.save(self.img_npy[i].as_posix(), x[0])
                    gb += self.img_npy[i].stat().st_size
                else:
                    self.imgs[i], self.img_hw0[i], self.img_hw[i] = x
                    gb += self.imgs[i].nbytes
                pbar.desc = f'{prefix}Caching images ({gb / 1E9:.1f}GB)'
            pbar.close()

    def cache_labels(self, path=Path('./labels.cache'), prefix=''):
        # Cache dataset labels, check images and read shapes
        x = {}  # dict
        nm, nf, ne, nc = 0, 0, 0, 0  # number missing, found, empty, duplicate
        pbar = tqdm(zip(self.img_files, self.label_files), desc='Scanning images', total=len(self.img_files))
        for i, (im_file, lb_file) in enumerate(pbar):
            try:
                # verify images
                im = Image.open(im_file)
                im.verify()  # PIL verify
                shape = exif_size(im)  # image size
                segments = []  # instance segments
                assert (shape[0] > 9) & (shape[1] > 9), f'image size {shape} <10 pixels'
                assert im.format.lower() in img_formats, f'invalid image format {im.format}'

                # verify labels
                if os.path.isfile(lb_file):
                    nf += 1  # label found
                    with open(lb_file, 'r') as f:
                        l = [x.split() for x in f.read().strip().splitlines()]
                        if any([len(x) > 8 for x in l]):  # is segment
                            classes = np.array([x[0] for x in l], dtype=np.float32)
                            segments = [np.array(x[1:], dtype=np.float32).reshape(-1, 2) for x in l]  # (cls, xy1...)
                            l = np.concatenate((classes.reshape(-1, 1), segments2boxes(segments)), 1)  # (cls, xywh)
                        l = np.array(l, dtype=np.float32)
                    if len(l):
                        assert l.shape[1] == 5, 'labels require 5 columns each'
                        assert (l >= 0).all(), 'negative labels'
                        assert (l[:, 1:] <= 1).all(), 'non-normalized or out of bounds coordinate labels'
                        assert np.unique(l, axis=0).shape[0] == l.shape[0], 'duplicate labels'
                    else:
                        ne += 1  # label empty
                        l = np.zeros((0, 5), dtype=np.float32)
                else:
                    nm += 1  # label missing
                    l = np.zeros((0, 5), dtype=np.float32)
                x[im_file] = [l, shape, segments]
            except Exception as e:
                nc += 1
                print(f'{prefix}WARNING: Ignoring corrupted image and/or label {im_file}: {e}')

            pbar.desc = f"{prefix}Scanning '{path.parent / path.stem}' images and labels... " \
                        f"{nf} found, {nm} missing, {ne} empty, {nc} corrupted"
        pbar.close()

        if nf == 0:
            print(f'{prefix}WARNING: No labels found in {path}. See {help_url}')

        x['hash'] = get_hash(self.label_files + self.img_files)
        x['results'] = nf, nm, ne, nc, i + 1
        x['version'] = 0.1  # cache version
        torch.save(x, path)  # save for next time
        logging.info(f'{prefix}New cache created: {path}')
        return x

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

    # def __iter__(self):
    #     self.count = -1
    #     print('ran dataset iter')
    #     #self.shuffled_vector = np.random.permutation(self.nF) if self.augment else np.arange(self.nF)
    #     return self

    def __getitem__(self, index):
        index = self.indices[index]  # linear, shuffled, or image_weights

        hyp = self.hyp
        mosaic = self.mosaic and random.random() < hyp['mosaic']
        if mosaic:
            # Load mosaic
            if random.random() < 0.8:
                img, labels = load_mosaic(self, index)
            else:
                img, labels = load_mosaic9(self, index)
            shapes = None

            # MixUp https://arxiv.org/pdf/1710.09412.pdf
            if random.random() < hyp['mixup']:
                if random.random() < 0.8:
                    img2, labels2 = load_mosaic(self, random.randint(0, len(self.labels) - 1))
                else:
                    img2, labels2 = load_mosaic9(self, random.randint(0, len(self.labels) - 1))
                r = np.random.beta(8.0, 8.0)  # mixup ratio, alpha=beta=8.0
                img = (img * r + img2 * (1 - r)).astype(np.uint8)
                labels = np.concatenate((labels, labels2), 0)

        else:
            # Load image
            img, (h0, w0), (h, w) = load_image(self, index)

            # Letterbox
            shape = self.batch_shapes[self.batch[index]] if self.rect else self.img_size  # final letterboxed shape
            img, ratio, pad = letterbox(img, shape, auto=False, scaleup=self.augment)
            shapes = (h0, w0), ((h / h0, w / w0), pad)  # for COCO mAP rescaling

            labels = self.labels[index].copy()
            if labels.size:  # normalized xywh to pixel xyxy format
                labels[:, 1:] = xywhn2xyxy(labels[:, 1:], ratio[0] * w, ratio[1] * h, padw=pad[0], padh=pad[1])

        if self.augment:
            # Augment imagespace
            if not mosaic:
                img, labels = random_perspective(img, labels,
                                                 degrees=hyp['degrees'],
                                                 translate=hyp['translate'],
                                                 scale=hyp['scale'],
                                                 shear=hyp['shear'],
                                                 perspective=hyp['perspective'])

            #img, labels = self.albumentations(img, labels)

            # Augment colorspace
            augment_hsv(img, hgain=hyp['hsv_h'], sgain=hyp['hsv_s'], vgain=hyp['hsv_v'])

            # Apply cutouts
            # if random.random() < 0.9:
            #     labels = cutout(img, labels)

            if random.random() < hyp['paste_in']:
                sample_labels, sample_images, sample_masks = [], [], [] 
                while len(sample_labels) < 30:
                    sample_labels_, sample_images_, sample_masks_ = load_samples(self, random.randint(0, len(self.labels) - 1))
                    sample_labels += sample_labels_
                    sample_images += sample_images_
                    sample_masks += sample_masks_
                    #print(len(sample_labels))
                    if len(sample_labels) == 0:
                        break
                labels = pastein(img, labels, sample_labels, sample_images, sample_masks)

        nL = len(labels)  # number of labels
        if nL:
            labels[:, 1:5] = xyxy2xywh(labels[:, 1:5])  # convert xyxy to xywh
            labels[:, [2, 4]] /= img.shape[0]  # normalized height 0-1
            labels[:, [1, 3]] /= img.shape[1]  # normalized width 0-1

        if self.augment:
            # flip up-down
            if random.random() < hyp['flipud']:
                img = np.flipud(img)
                if nL:
                    labels[:, 2] = 1 - labels[:, 2]

            # flip left-right
            if random.random() < hyp['fliplr']:
                img = np.fliplr(img)
                if nL:
                    labels[:, 1] = 1 - labels[:, 1]

        labels_out = torch.zeros((nL, 6))
        if nL:
            labels_out[:, 1:] = torch.from_numpy(labels)

        # Convert
        img = img[:, :, ::-1].transpose(2, 0, 1)  # BGR to RGB, to 3x416x416
        img = np.ascontiguousarray(img)

        return torch.from_numpy(img), labels_out, self.img_files[index], shapes

    @staticmethod
    def collate_fn(batch):
        img, label, path, shapes = zip(*batch)  # transposed
        for i, l in enumerate(label):
            l[:, 0] = i  # add target image index for build_targets()
        return torch.stack(img, 0), torch.cat(label, 0), path, shapes

    @staticmethod
    def collate_fn4(batch):
        img, label, path, shapes = zip(*batch)  # transposed
        n = len(shapes) // 4
        img4, label4, path4, shapes4 = [], [], path[:n], shapes[:n]

        ho = torch.tensor([[0., 0, 0, 1, 0, 0]])
        wo = torch.tensor([[0., 0, 1, 0, 0, 0]])
        s = torch.tensor([[1, 1, .5, .5, .5, .5]])  # scale
        for i in range(n):  # zidane torch.zeros(16,3,720,1280)  # BCHW
            i *= 4
            if random.random() < 0.5:
                im = F.interpolate(img[i].unsqueeze(0).float(), scale_factor=2., mode='bilinear', align_corners=False)[
                    0].type(img[i].type())
                l = label[i]
            else:
                im = torch.cat((torch.cat((img[i], img[i + 1]), 1), torch.cat((img[i + 2], img[i + 3]), 1)), 2)
                l = torch.cat((label[i], label[i + 1] + ho, label[i + 2] + wo, label[i + 3] + ho + wo), 0) * s
            img4.append(im)
            label4.append(l)

        for i, l in enumerate(label4):
            l[:, 0] = i  # add target image index for build_targets()

        return torch.stack(img4, 0), torch.cat(label4, 0), path4, shapes4

class InfiniteDataLoader(torch.utils.data.dataloader.DataLoader):
    """ Dataloader that reuses workers

    Uses same syntax as vanilla DataLoader
    """

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        object.__setattr__(self, 'batch_sampler', _RepeatSampler(self.batch_sampler))
        self.iterator = super().__iter__()

    def __len__(self):
        return len(self.batch_sampler.sampler)

    def __iter__(self):
        for i in range(len(self)):
            yield next(self.iterator)

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