datasets.py

# Dataset utils and dataloaders

import glob
import logging
import math
import os
import random
import shutil
import time
from itertools import repeat
from multiprocessing.pool import ThreadPool
from pathlib import Path
from threading import Thread

import cv2
import numpy as np
import torch
import torch.nn.functional as F
from PIL import Image, ExifTags
from torch.utils.data import Dataset
from tqdm import tqdm

import pickle
from copy import deepcopy
#from pycocotools import mask as maskUtils
from torchvision.utils import save_image
from torchvision.ops import roi_pool, roi_align, ps_roi_pool, ps_roi_align

from utils.general import check_requirements, xyxy2xywh, xywh2xyxy, xywhn2xyxy, xyn2xy, segment2box, segments2boxes, \
    resample_segments, clean_str
from utils.torch_utils import torch_distributed_zero_first

# Parameters
help_url = 'https://github.com/ultralytics/yolov5/wiki/Train-Custom-Data'
img_formats = ['bmp', 'jpg', 'jpeg', 'png', 'tif', 'tiff', 'dng', 'webp', 'mpo']  # acceptable image suffixes
vid_formats = ['mov', 'avi', 'mp4', 'mpg', 'mpeg', 'm4v', 'wmv', 'mkv']  # acceptable video suffixes
logger = logging.getLogger(__name__)

# Get orientation exif tag
for orientation in ExifTags.TAGS.keys():
    if ExifTags.TAGS[orientation] == 'Orientation':
        break


def get_hash(files):
    # Returns a single hash value of a list of files
    return sum(os.path.getsize(f) for f in files if os.path.isfile(f))


def exif_size(img):
    # Returns exif-corrected PIL size
    s = img.size  # (width, height)
    try:
        rotation = dict(img._getexif().items())[orientation]
        if rotation == 6:  # rotation 270
            s = (s[1], s[0])
        elif rotation == 8:  # rotation 90
            s = (s[1], s[0])
    except:
        pass

    return s


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):
        if opt.dataset == 'COCO':
            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)
        else:
            dataset = LoadImagesAndLabelsCustom(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 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)


class _RepeatSampler(object):
    """ Sampler that repeats forever

    Args:
        sampler (Sampler)
    """

    def __init__(self, sampler):
        self.sampler = sampler

    def __iter__(self):
        while True:
            yield from iter(self.sampler)


class LoadImages:  # for inference
    def __init__(self, path, img_size=640, stride=32):
        p = str(Path(path).absolute())  # os-agnostic absolute path
        if '*' in p:
            files = sorted(glob.glob(p, recursive=True))  # glob
        elif os.path.isdir(p):
            files = sorted(glob.glob(os.path.join(p, '*.*')))  # dir
        elif os.path.isfile(p):
            files = [p]  # files
        else:
            raise Exception(f'ERROR: {p} does not exist')

        images = [x for x in files if x.split('.')[-1].lower() in img_formats]
        videos = [x for x in files if x.split('.')[-1].lower() in vid_formats]
        ni, nv = len(images), len(videos)

        self.img_size = img_size
        self.stride = stride
        self.files = images + videos
        self.nf = ni + nv  # number of files
        self.video_flag = [False] * ni + [True] * nv
        self.mode = 'image'
        if any(videos):
            self.new_video(videos[0])  # new video
        else:
            self.cap = None
        assert self.nf > 0, f'No images or videos found in {p}. ' \
                            f'Supported formats are:\nimages: {img_formats}\nvideos: {vid_formats}'

    def __iter__(self):
        self.count = 0
        return self

    def __next__(self):
        if self.count == self.nf:
            raise StopIteration
        path = self.files[self.count]

        if self.video_flag[self.count]:
            # Read video
            self.mode = 'video'
            ret_val, img0 = self.cap.read()
            if not ret_val:
                self.count += 1
                self.cap.release()
                if self.count == self.nf:  # last video
                    raise StopIteration
                else:
                    path = self.files[self.count]
                    self.new_video(path)
                    ret_val, img0 = self.cap.read()

            self.frame += 1
            print(f'video {self.count + 1}/{self.nf} ({self.frame}/{self.nframes}) {path}: ', end='')

        else:
            # Read image
            self.count += 1
            img0 = cv2.imread(path)  # BGR
            assert img0 is not None, 'Image Not Found ' + path
            #print(f'image {self.count}/{self.nf} {path}: ', end='')

        # Padded resize
        img = letterbox(img0, self.img_size, stride=self.stride)[0]

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

        return path, img, img0, self.cap

    def new_video(self, path):
        self.frame = 0
        self.cap = cv2.VideoCapture(path)
        self.nframes = int(self.cap.get(cv2.CAP_PROP_FRAME_COUNT))

    def __len__(self):
        return self.nf  # number of files


class LoadWebcam:  # for inference
    def __init__(self, pipe='0', img_size=640, stride=32):
        self.img_size = img_size
        self.stride = stride

        if pipe.isnumeric():
            pipe = eval(pipe)  # local camera
        # pipe = 'rtsp://192.168.1.64/1'  # IP camera
        # pipe = 'rtsp://username:password@192.168.1.64/1'  # IP camera with login
        # pipe = 'http://wmccpinetop.axiscam.net/mjpg/video.mjpg'  # IP golf camera

        self.pipe = pipe
        self.cap = cv2.VideoCapture(pipe)  # video capture object
        self.cap.set(cv2.CAP_PROP_BUFFERSIZE, 3)  # set buffer size

    def __iter__(self):
        self.count = -1
        return self

    def __next__(self):
        self.count += 1
        if cv2.waitKey(1) == ord('q'):  # q to quit
            self.cap.release()
            cv2.destroyAllWindows()
            raise StopIteration

        # Read frame
        if self.pipe == 0:  # local camera
            ret_val, img0 = self.cap.read()
            img0 = cv2.flip(img0, 1)  # flip left-right
        else:  # IP camera
            n = 0
            while True:
                n += 1
                self.cap.grab()
                if n % 30 == 0:  # skip frames
                    ret_val, img0 = self.cap.retrieve()
                    if ret_val:
                        break

        # Print
        assert ret_val, f'Camera Error {self.pipe}'
        img_path = 'webcam.jpg'
        print(f'webcam {self.count}: ', end='')

        # Padded resize
        img = letterbox(img0, self.img_size, stride=self.stride)[0]

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

        return img_path, img, img0, None

    def __len__(self):
        return 0


class LoadStreams:  # multiple IP or RTSP cameras
    def __init__(self, sources='streams.txt', img_size=640, stride=32):
        self.mode = 'stream'
        self.img_size = img_size
        self.stride = stride

        if os.path.isfile(sources):
            with open(sources, 'r') as f:
                sources = [x.strip() for x in f.read().strip().splitlines() if len(x.strip())]
        else:
            sources = [sources]

        n = len(sources)
        self.imgs = [None] * n
        self.sources = [clean_str(x) for x in sources]  # clean source names for later
        for i, s in enumerate(sources):
            # Start the thread to read frames from the video stream
            print(f'{i + 1}/{n}: {s}... ', end='')
            url = eval(s) if s.isnumeric() else s
            if 'youtube.com/' in url or 'youtu.be/' in url:  # if source is YouTube video
                check_requirements(('pafy', 'youtube_dl'))
                import pafy
                url = pafy.new(url).getbest(preftype="mp4").url
            cap = cv2.VideoCapture(url)
            assert cap.isOpened(), f'Failed to open {s}'
            w = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
            h = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
            self.fps = cap.get(cv2.CAP_PROP_FPS) % 100

            _, self.imgs[i] = cap.read()  # guarantee first frame
            thread = Thread(target=self.update, args=([i, cap]), daemon=True)
            print(f' success ({w}x{h} at {self.fps:.2f} FPS).')
            thread.start()
        print('')  # newline

        # check for common shapes
        s = np.stack([letterbox(x, self.img_size, stride=self.stride)[0].shape for x in self.imgs], 0)  # shapes
        self.rect = np.unique(s, axis=0).shape[0] == 1  # rect inference if all shapes equal
        if not self.rect:
            print('WARNING: Different stream shapes detected. For optimal performance supply similarly-shaped streams.')

    def update(self, index, cap):
        # Read next stream frame in a daemon thread
        n = 0
        while cap.isOpened():
            n += 1
            # _, self.imgs[index] = cap.read()
            cap.grab()
            if n == 4:  # read every 4th frame
                success, im = cap.retrieve()
                self.imgs[index] = im if success else self.imgs[index] * 0
                n = 0
            time.sleep(1 / self.fps)  # wait time

    def __iter__(self):
        self.count = -1
        return self

    def __next__(self):
        self.count += 1
        img0 = self.imgs.copy()
        if cv2.waitKey(1) == ord('q'):  # q to quit
            cv2.destroyAllWindows()
            raise StopIteration

        # Letterbox
        img = [letterbox(x, self.img_size, auto=self.rect, stride=self.stride)[0] for x in img0]

        # Stack
        img = np.stack(img, 0)

        # Convert
        img = img[:, :, :, ::-1].transpose(0, 3, 1, 2)  # BGR to RGB, to bsx3x416x416
        img = np.ascontiguousarray(img)

        return self.sources, img, img0, None

    def __len__(self):
        return 0  # 1E12 frames = 32 streams at 30 FPS for 30 years


def img2label_paths(img_paths):
    # Define label paths as a function of image paths
    sa, sb = os.sep + 'images' + os.sep, os.sep + 'labels' + os.sep  # /images/, /labels/ substrings
    return ['txt'.join(x.replace(sa, sb, 1).rsplit(x.split('.')[-1], 1)) for x in img_paths]


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()  # 数据集中每个图片的路径
                        parent = str(p.parent) + os.sep  # 代码文件夹的上一级
                        # 遍历t 找到图片路径 注意这里默认数据集和代码在一个文件夹下
                        f += [x.replace('./', parent) if x.startswith('./') else x for x in t]  # local to global path 变成全局路径
                        # 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 得到真值txt文件路径
        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(np.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(np.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


def img2label_paths_VisDrone(img_paths):
    """
    img_paths: List[str]
    """
    # 默认标签和图片文件夹在同一目录
    return [p.replace('images', 'labels').replace('jpg', 'txt') for p in img_paths]



class LoadImagesAndLabelsCustom(LoadImagesAndLabels):
    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, prefix=''):
        # super().__init__(path, img_size, batch_size, augment, hyp, rect, image_weights, cache_images, single_cls, stride, pad, 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    

        PREFIX = '/data/wujiapeng/datasets/'
        path = Path(path)
        assert path.is_file(), 'wrong format for VisDrone'

        image_files = []  # 提取txt中的内容

        with open(path, 'r') as t:
            lines = t.read().strip().splitlines()

            image_files += [os.path.join(PREFIX, line) for line in lines]

        t.close()
        self.img_files = image_files
        self.label_files = img2label_paths_VisDrone(self.img_files)  # 真值txt的路径
        cache_path = path.with_suffix('.cache')  # 创建.cache

        if cache_path.is_file():
            cache, exists = torch.load(cache_path), True  # load
        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_VisDrone(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(np.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(np.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()

# Ancillary functions --------------------------------------------------------------------------------------------------
def load_image(self, index):
    # loads 1 image from dataset, returns img, original hw, resized hw
    img = self.imgs[index]
    if img is None:  # not cached
        path = self.img_files[index]
        img = cv2.imread(path)  # BGR
        assert img is not None, 'Image Not Found ' + path
        h0, w0 = img.shape[:2]  # orig hw
        r = self.img_size / max(h0, w0)  # resize image to img_size
        if r != 1:  # always resize down, only resize up if training with augmentation
            interp = cv2.INTER_AREA if r < 1 and not self.augment else cv2.INTER_LINEAR
            img = cv2.resize(img, (int(w0 * r), int(h0 * r)), interpolation=interp)
        return img, (h0, w0), img.shape[:2]  # img, hw_original, hw_resized
    else:
        return self.imgs[index], self.img_hw0[index], self.img_hw[index]  # img, hw_original, hw_resized


def augment_hsv(img, hgain=0.5, sgain=0.5, vgain=0.5):
    r = np.random.uniform(-1, 1, 3) * [hgain, sgain, vgain] + 1  # random gains
    hue, sat, val = cv2.split(cv2.cvtColor(img, cv2.COLOR_BGR2HSV))
    dtype = img.dtype  # uint8

    x = np.arange(0, 256, dtype=np.int16)
    lut_hue = ((x * r[0]) % 180).astype(dtype)
    lut_sat = np.clip(x * r[1], 0, 255).astype(dtype)
    lut_val = np.clip(x * r[2], 0, 255).astype(dtype)

    img_hsv = cv2.merge((cv2.LUT(hue, lut_hue), cv2.LUT(sat, lut_sat), cv2.LUT(val, lut_val))).astype(dtype)
    cv2.cvtColor(img_hsv, cv2.COLOR_HSV2BGR, dst=img)  # no return needed


def hist_equalize(img, clahe=True, bgr=False):
    # Equalize histogram on BGR image 'img' with img.shape(n,m,3) and range 0-255
    yuv = cv2.cvtColor(img, cv2.COLOR_BGR2YUV if bgr else cv2.COLOR_RGB2YUV)
    if clahe:
        c = cv2.createCLAHE(clipLimit=2.0, tileGridSize=(8, 8))
        yuv[:, :, 0] = c.apply(yuv[:, :, 0])
    else:
        yuv[:, :, 0] = cv2.equalizeHist(yuv[:, :, 0])  # equalize Y channel histogram
    return cv2.cvtColor(yuv, cv2.COLOR_YUV2BGR if bgr else cv2.COLOR_YUV2RGB)  # convert YUV image to RGB


def load_mosaic(self, index):
    # loads images in a 4-mosaic

    labels4, segments4 = [], []
    s = self.img_size
    yc, xc = [int(random.uniform(-x, 2 * s + x)) for x in self.mosaic_border]  # mosaic center x, y
    indices = [index] + random.choices(self.indices, k=3)  # 3 additional image indices
    for i, index in enumerate(indices):
        # Load image
        img, _, (h, w) = load_image(self, index)

        # place img in img4
        if i == 0:  # top left
            img4 = np.full((s * 2, s * 2, img.shape[2]), 114, dtype=np.uint8)  # base image with 4 tiles
            x1a, y1a, x2a, y2a = max(xc - w, 0), max(yc - h, 0), xc, yc  # xmin, ymin, xmax, ymax (large image)
            x1b, y1b, x2b, y2b = w - (x2a - x1a), h - (y2a - y1a), w, h  # xmin, ymin, xmax, ymax (small image)
        elif i == 1:  # top right
            x1a, y1a, x2a, y2a = xc, max(yc - h, 0), min(xc + w, s * 2), yc
            x1b, y1b, x2b, y2b = 0, h - (y2a - y1a), min(w, x2a - x1a), h
        elif i == 2:  # bottom left
            x1a, y1a, x2a, y2a = max(xc - w, 0), yc, xc, min(s * 2, yc + h)
            x1b, y1b, x2b, y2b = w - (x2a - x1a), 0, w, min(y2a - y1a, h)
        elif i == 3:  # bottom right
            x1a, y1a, x2a, y2a = xc, yc, min(xc + w, s * 2), min(s * 2, yc + h)
            x1b, y1b, x2b, y2b = 0, 0, min(w, x2a - x1a), min(y2a - y1a, h)

        img4[y1a:y2a, x1a:x2a] = img[y1b:y2b, x1b:x2b]  # img4[ymin:ymax, xmin:xmax]
        padw = x1a - x1b
        padh = y1a - y1b

        # Labels
        labels, segments = self.labels[index].copy(), self.segments[index].copy()
        if labels.size:
            labels[:, 1:] = xywhn2xyxy(labels[:, 1:], w, h, padw, padh)  # normalized xywh to pixel xyxy format
            segments = [xyn2xy(x, w, h, padw, padh) for x in segments]
        labels4.append(labels)
        segments4.extend(segments)

    # Concat/clip labels
    labels4 = np.concatenate(labels4, 0)
    for x in (labels4[:, 1:], *segments4):
        np.clip(x, 0, 2 * s, out=x)  # clip when using random_perspective()
    # img4, labels4 = replicate(img4, labels4)  # replicate

    # Augment
    #img4, labels4, segments4 = remove_background(img4, labels4, segments4)
    #sample_segments(img4, labels4, segments4, probability=self.hyp['copy_paste'])
    img4, labels4, segments4 = copy_paste(img4, labels4, segments4, probability=self.hyp['copy_paste'])
    img4, labels4 = random_perspective(img4, labels4, segments4,
                                       degrees=self.hyp['degrees'],
                                       translate=self.hyp['translate'],
                                       scale=self.hyp['scale'],
                                       shear=self.hyp['shear'],
                                       perspective=self.hyp['perspective'],
                                       border=self.mosaic_border)  # border to remove

    return img4, labels4


def load_mosaic9(self, index):
    # loads images in a 9-mosaic

    labels9, segments9 = [], []
    s = self.img_size
    indices = [index] + random.choices(self.indices, k=8)  # 8 additional image indices
    for i, index in enumerate(indices):
        # Load image
        img, _, (h, w) = load_image(self, index)

        # place img in img9
        if i == 0:  # center
            img9 = np.full((s * 3, s * 3, img.shape[2]), 114, dtype=np.uint8)  # base image with 4 tiles
            h0, w0 = h, w
            c = s, s, s + w, s + h  # xmin, ymin, xmax, ymax (base) coordinates
        elif i == 1:  # top
            c = s, s - h, s + w, s
        elif i == 2:  # top right
            c = s + wp, s - h, s + wp + w, s
        elif i == 3:  # right
            c = s + w0, s, s + w0 + w, s + h
        elif i == 4:  # bottom right
            c = s + w0, s + hp, s + w0 + w, s + hp + h
        elif i == 5:  # bottom
            c = s + w0 - w, s + h0, s + w0, s + h0 + h
        elif i == 6:  # bottom left
            c = s + w0 - wp - w, s + h0, s + w0 - wp, s + h0 + h
        elif i == 7:  # left
            c = s - w, s + h0 - h, s, s + h0
        elif i == 8:  # top left
            c = s - w, s + h0 - hp - h, s, s + h0 - hp

        padx, pady = c[:2]
        x1, y1, x2, y2 = [max(x, 0) for x in c]  # allocate coords

        # Labels
        labels, segments = self.labels[index].copy(), self.segments[index].copy()
        if labels.size:
            labels[:, 1:] = xywhn2xyxy(labels[:, 1:], w, h, padx, pady)  # normalized xywh to pixel xyxy format
            segments = [xyn2xy(x, w, h, padx, pady) for x in segments]
        labels9.append(labels)
        segments9.extend(segments)

        # Image
        img9[y1:y2, x1:x2] = img[y1 - pady:, x1 - padx:]  # img9[ymin:ymax, xmin:xmax]
        hp, wp = h, w  # height, width previous

    # Offset
    yc, xc = [int(random.uniform(0, s)) for _ in self.mosaic_border]  # mosaic center x, y
    img9 = img9[yc:yc + 2 * s, xc:xc + 2 * s]

    # Concat/clip labels
    labels9 = np.concatenate(labels9, 0)
    labels9[:, [1, 3]] -= xc
    labels9[:, [2, 4]] -= yc
    c = np.array([xc, yc])  # centers
    segments9 = [x - c for x in segments9]

    for x in (labels9[:, 1:], *segments9):
        np.clip(x, 0, 2 * s, out=x)  # clip when using random_perspective()
    # img9, labels9 = replicate(img9, labels9)  # replicate

    # Augment
    #img9, labels9, segments9 = remove_background(img9, labels9, segments9)
    img9, labels9, segments9 = copy_paste(img9, labels9, segments9, probability=self.hyp['copy_paste'])
    img9, labels9 = random_perspective(img9, labels9, segments9,
                                       degrees=self.hyp['degrees'],
                                       translate=self.hyp['translate'],
                                       scale=self.hyp['scale'],
                                       shear=self.hyp['shear'],
                                       perspective=self.hyp['perspective'],
                                       border=self.mosaic_border)  # border to remove

    return img9, labels9


def load_samples(self, index):
    # loads images in a 4-mosaic

    labels4, segments4 = [], []
    s = self.img_size
    yc, xc = [int(random.uniform(-x, 2 * s + x)) for x in self.mosaic_border]  # mosaic center x, y
    indices = [index] + random.choices(self.indices, k=3)  # 3 additional image indices
    for i, index in enumerate(indices):
        # Load image
        img, _, (h, w) = load_image(self, index)

        # place img in img4
        if i == 0:  # top left
            img4 = np.full((s * 2, s * 2, img.shape[2]), 114, dtype=np.uint8)  # base image with 4 tiles
            x1a, y1a, x2a, y2a = max(xc - w, 0), max(yc - h, 0), xc, yc  # xmin, ymin, xmax, ymax (large image)
            x1b, y1b, x2b, y2b = w - (x2a - x1a), h - (y2a - y1a), w, h  # xmin, ymin, xmax, ymax (small image)
        elif i == 1:  # top right
            x1a, y1a, x2a, y2a = xc, max(yc - h, 0), min(xc + w, s * 2), yc
            x1b, y1b, x2b, y2b = 0, h - (y2a - y1a), min(w, x2a - x1a), h
        elif i == 2:  # bottom left
            x1a, y1a, x2a, y2a = max(xc - w, 0), yc, xc, min(s * 2, yc + h)
            x1b, y1b, x2b, y2b = w - (x2a - x1a), 0, w, min(y2a - y1a, h)
        elif i == 3:  # bottom right
            x1a, y1a, x2a, y2a = xc, yc, min(xc + w, s * 2), min(s * 2, yc + h)
            x1b, y1b, x2b, y2b = 0, 0, min(w, x2a - x1a), min(y2a - y1a, h)

        img4[y1a:y2a, x1a:x2a] = img[y1b:y2b, x1b:x2b]  # img4[ymin:ymax, xmin:xmax]
        padw = x1a - x1b
        padh = y1a - y1b

        # Labels
        labels, segments = self.labels[index].copy(), self.segments[index].copy()
        if labels.size:
            labels[:, 1:] = xywhn2xyxy(labels[:, 1:], w, h, padw, padh)  # normalized xywh to pixel xyxy format
            segments = [xyn2xy(x, w, h, padw, padh) for x in segments]
        labels4.append(labels)
        segments4.extend(segments)

    # Concat/clip labels
    labels4 = np.concatenate(labels4, 0)
    for x in (labels4[:, 1:], *segments4):
        np.clip(x, 0, 2 * s, out=x)  # clip when using random_perspective()
    # img4, labels4 = replicate(img4, labels4)  # replicate

    # Augment
    #img4, labels4, segments4 = remove_background(img4, labels4, segments4)
    sample_labels, sample_images, sample_masks = sample_segments(img4, labels4, segments4, probability=0.5)

    return sample_labels, sample_images, sample_masks


def copy_paste(img, labels, segments, probability=0.5):
    # Implement Copy-Paste augmentation https://arxiv.org/abs/2012.07177, labels as nx5 np.array(cls, xyxy)
    n = len(segments)
    if probability and n:
        h, w, c = img.shape  # height, width, channels
        im_new = np.zeros(img.shape, np.uint8)
        for j in random.sample(range(n), k=round(probability * n)):
            l, s = labels[j], segments[j]
            box = w - l[3], l[2], w - l[1], l[4]
            ioa = bbox_ioa(box, labels[:, 1:5])  # intersection over area
            if (ioa < 0.30).all():  # allow 30% obscuration of existing labels
                labels = np.concatenate((labels, [[l[0], *box]]), 0)
                segments.append(np.concatenate((w - s[:, 0:1], s[:, 1:2]), 1))
                cv2.drawContours(im_new, [segments[j].astype(np.int32)], -1, (255, 255, 255), cv2.FILLED)

        result = cv2.bitwise_and(src1=img, src2=im_new)
        result = cv2.flip(result, 1)  # augment segments (flip left-right)
        i = result > 0  # pixels to replace
        # i[:, :] = result.max(2).reshape(h, w, 1)  # act over ch
        img[i] = result[i]  # cv2.imwrite('debug.jpg', img)  # debug

    return img, labels, segments


def remove_background(img, labels, segments):
    # Implement Copy-Paste augmentation https://arxiv.org/abs/2012.07177, labels as nx5 np.array(cls, xyxy)
    n = len(segments)
    h, w, c = img.shape  # height, width, channels
    im_new = np.zeros(img.shape, np.uint8)
    img_new = np.ones(img.shape, np.uint8) * 114
    for j in range(n):
        cv2.drawContours(im_new, [segments[j].astype(np.int32)], -1, (255, 255, 255), cv2.FILLED)

        result = cv2.bitwise_and(src1=img, src2=im_new)
        
        i = result > 0  # pixels to replace
        img_new[i] = result[i]  # cv2.imwrite('debug.jpg', img)  # debug

    return img_new, labels, segments


def sample_segments(img, labels, segments, probability=0.5):
    # Implement Copy-Paste augmentation https://arxiv.org/abs/2012.07177, labels as nx5 np.array(cls, xyxy)
    n = len(segments)
    sample_labels = []
    sample_images = []
    sample_masks = []
    if probability and n:
        h, w, c = img.shape  # height, width, channels
        for j in random.sample(range(n), k=round(probability * n)):
            l, s = labels[j], segments[j]
            box = l[1].astype(int).clip(0,w-1), l[2].astype(int).clip(0,h-1), l[3].astype(int).clip(0,w-1), l[4].astype(int).clip(0,h-1) 
            
            #print(box)
            if (box[2] <= box[0]) or (box[3] <= box[1]):
                continue
            
            sample_labels.append(l[0])
            
            mask = np.zeros(img.shape, np.uint8)
            
            cv2.drawContours(mask, [segments[j].astype(np.int32)], -1, (255, 255, 255), cv2.FILLED)
            sample_masks.append(mask[box[1]:box[3],box[0]:box[2],:])
            
            result = cv2.bitwise_and(src1=img, src2=mask)
            i = result > 0  # pixels to replace
            mask[i] = result[i]  # cv2.imwrite('debug.jpg', img)  # debug
            #print(box)
            sample_images.append(mask[box[1]:box[3],box[0]:box[2],:])

    return sample_labels, sample_images, sample_masks


def replicate(img, labels):
    # Replicate labels
    h, w = img.shape[:2]
    boxes = labels[:, 1:].astype(int)
    x1, y1, x2, y2 = boxes.T
    s = ((x2 - x1) + (y2 - y1)) / 2  # side length (pixels)
    for i in s.argsort()[:round(s.size * 0.5)]:  # smallest indices
        x1b, y1b, x2b, y2b = boxes[i]
        bh, bw = y2b - y1b, x2b - x1b
        yc, xc = int(random.uniform(0, h - bh)), int(random.uniform(0, w - bw))  # offset x, y
        x1a, y1a, x2a, y2a = [xc, yc, xc + bw, yc + bh]
        img[y1a:y2a, x1a:x2a] = img[y1b:y2b, x1b:x2b]  # img4[ymin:ymax, xmin:xmax]
        labels = np.append(labels, [[labels[i, 0], x1a, y1a, x2a, y2a]], axis=0)

    return img, labels


def letterbox(img, new_shape=(640, 640), color=(114, 114, 114), auto=True, scaleFill=False, scaleup=True, stride=32):
    # Resize and pad image while meeting stride-multiple constraints
    shape = img.shape[:2]  # current shape [height, width]
    if isinstance(new_shape, int):
        new_shape = (new_shape, new_shape)

    # Scale ratio (new / old)
    r = min(new_shape[0] / shape[0], new_shape[1] / shape[1])
    if not scaleup:  # only scale down, do not scale up (for better test mAP)
        r = min(r, 1.0)

    # Compute padding
    ratio = r, r  # width, height ratios
    new_unpad = int(round(shape[1] * r)), int(round(shape[0] * r))
    dw, dh = new_shape[1] - new_unpad[0], new_shape[0] - new_unpad[1]  # wh padding
    if auto:  # minimum rectangle
        dw, dh = np.mod(dw, stride), np.mod(dh, stride)  # wh padding
    elif scaleFill:  # stretch
        dw, dh = 0.0, 0.0
        new_unpad = (new_shape[1], new_shape[0])
        ratio = new_shape[1] / shape[1], new_shape[0] / shape[0]  # width, height ratios

    dw /= 2  # divide padding into 2 sides
    dh /= 2

    if shape[::-1] != new_unpad:  # resize
        img = cv2.resize(img, new_unpad, interpolation=cv2.INTER_LINEAR)
    top, bottom = int(round(dh - 0.1)), int(round(dh + 0.1))
    left, right = int(round(dw - 0.1)), int(round(dw + 0.1))
    img = cv2.copyMakeBorder(img, top, bottom, left, right, cv2.BORDER_CONSTANT, value=color)  # add border
    return img, ratio, (dw, dh)


def random_perspective(img, targets=(), segments=(), degrees=10, translate=.1, scale=.1, shear=10, perspective=0.0,
                       border=(0, 0)):
    # torchvision.transforms.RandomAffine(degrees=(-10, 10), translate=(.1, .1), scale=(.9, 1.1), shear=(-10, 10))
    # targets = [cls, xyxy]

    height = img.shape[0] + border[0] * 2  # shape(h,w,c)
    width = img.shape[1] + border[1] * 2

    # Center
    C = np.eye(3)
    C[0, 2] = -img.shape[1] / 2  # x translation (pixels)
    C[1, 2] = -img.shape[0] / 2  # y translation (pixels)

    # Perspective
    P = np.eye(3)
    P[2, 0] = random.uniform(-perspective, perspective)  # x perspective (about y)
    P[2, 1] = random.uniform(-perspective, perspective)  # y perspective (about x)

    # Rotation and Scale
    R = np.eye(3)
    a = random.uniform(-degrees, degrees)
    # a += random.choice([-180, -90, 0, 90])  # add 90deg rotations to small rotations
    s = random.uniform(1 - scale, 1.1 + scale)
    # s = 2 ** random.uniform(-scale, scale)
    R[:2] = cv2.getRotationMatrix2D(angle=a, center=(0, 0), scale=s)

    # Shear
    S = np.eye(3)
    S[0, 1] = math.tan(random.uniform(-shear, shear) * math.pi / 180)  # x shear (deg)
    S[1, 0] = math.tan(random.uniform(-shear, shear) * math.pi / 180)  # y shear (deg)

    # Translation
    T = np.eye(3)
    T[0, 2] = random.uniform(0.5 - translate, 0.5 + translate) * width  # x translation (pixels)
    T[1, 2] = random.uniform(0.5 - translate, 0.5 + translate) * height  # y translation (pixels)

    # Combined rotation matrix
    M = T @ S @ R @ P @ C  # order of operations (right to left) is IMPORTANT
    if (border[0] != 0) or (border[1] != 0) or (M != np.eye(3)).any():  # image changed
        if perspective:
            img = cv2.warpPerspective(img, M, dsize=(width, height), borderValue=(114, 114, 114))
        else:  # affine
            img = cv2.warpAffine(img, M[:2], dsize=(width, height), borderValue=(114, 114, 114))

    # Visualize
    # import matplotlib.pyplot as plt
    # ax = plt.subplots(1, 2, figsize=(12, 6))[1].ravel()
    # ax[0].imshow(img[:, :, ::-1])  # base
    # ax[1].imshow(img2[:, :, ::-1])  # warped

    # Transform label coordinates
    n = len(targets)
    if n:
        use_segments = any(x.any() for x in segments)
        new = np.zeros((n, 4))
        if use_segments:  # warp segments
            segments = resample_segments(segments)  # upsample
            for i, segment in enumerate(segments):
                xy = np.ones((len(segment), 3))
                xy[:, :2] = segment
                xy = xy @ M.T  # transform
                xy = xy[:, :2] / xy[:, 2:3] if perspective else xy[:, :2]  # perspective rescale or affine

                # clip
                new[i] = segment2box(xy, width, height)

        else:  # warp boxes
            xy = np.ones((n * 4, 3))
            xy[:, :2] = targets[:, [1, 2, 3, 4, 1, 4, 3, 2]].reshape(n * 4, 2)  # x1y1, x2y2, x1y2, x2y1
            xy = xy @ M.T  # transform
            xy = (xy[:, :2] / xy[:, 2:3] if perspective else xy[:, :2]).reshape(n, 8)  # perspective rescale or affine

            # create new boxes
            x = xy[:, [0, 2, 4, 6]]
            y = xy[:, [1, 3, 5, 7]]
            new = np.concatenate((x.min(1), y.min(1), x.max(1), y.max(1))).reshape(4, n).T

            # clip
            new[:, [0, 2]] = new[:, [0, 2]].clip(0, width)
            new[:, [1, 3]] = new[:, [1, 3]].clip(0, height)

        # filter candidates
        i = box_candidates(box1=targets[:, 1:5].T * s, box2=new.T, area_thr=0.01 if use_segments else 0.10)
        targets = targets[i]
        targets[:, 1:5] = new[i]

    return img, targets


def box_candidates(box1, box2, wh_thr=2, ar_thr=20, area_thr=0.1, eps=1e-16):  # box1(4,n), box2(4,n)
    # Compute candidate boxes: box1 before augment, box2 after augment, wh_thr (pixels), aspect_ratio_thr, area_ratio
    w1, h1 = box1[2] - box1[0], box1[3] - box1[1]
    w2, h2 = box2[2] - box2[0], box2[3] - box2[1]
    ar = np.maximum(w2 / (h2 + eps), h2 / (w2 + eps))  # aspect ratio
    return (w2 > wh_thr) & (h2 > wh_thr) & (w2 * h2 / (w1 * h1 + eps) > area_thr) & (ar < ar_thr)  # candidates


def bbox_ioa(box1, box2):
    # Returns the intersection over box2 area given box1, box2. box1 is 4, box2 is nx4. boxes are x1y1x2y2
    box2 = box2.transpose()

    # Get the coordinates of bounding boxes
    b1_x1, b1_y1, b1_x2, b1_y2 = box1[0], box1[1], box1[2], box1[3]
    b2_x1, b2_y1, b2_x2, b2_y2 = box2[0], box2[1], box2[2], box2[3]

    # Intersection area
    inter_area = (np.minimum(b1_x2, b2_x2) - np.maximum(b1_x1, b2_x1)).clip(0) * \
                 (np.minimum(b1_y2, b2_y2) - np.maximum(b1_y1, b2_y1)).clip(0)

    # box2 area
    box2_area = (b2_x2 - b2_x1) * (b2_y2 - b2_y1) + 1e-16

    # Intersection over box2 area
    return inter_area / box2_area
    

def cutout(image, labels):
    # Applies image cutout augmentation https://arxiv.org/abs/1708.04552
    h, w = image.shape[:2]

    # create random masks
    scales = [0.5] * 1 + [0.25] * 2 + [0.125] * 4 + [0.0625] * 8 + [0.03125] * 16  # image size fraction
    for s in scales:
        mask_h = random.randint(1, int(h * s))
        mask_w = random.randint(1, int(w * s))

        # box
        xmin = max(0, random.randint(0, w) - mask_w // 2)
        ymin = max(0, random.randint(0, h) - mask_h // 2)
        xmax = min(w, xmin + mask_w)
        ymax = min(h, ymin + mask_h)

        # apply random color mask
        image[ymin:ymax, xmin:xmax] = [random.randint(64, 191) for _ in range(3)]

        # return unobscured labels
        if len(labels) and s > 0.03:
            box = np.array([xmin, ymin, xmax, ymax], dtype=np.float32)
            ioa = bbox_ioa(box, labels[:, 1:5])  # intersection over area
            labels = labels[ioa < 0.60]  # remove >60% obscured labels

    return labels
    

def pastein(image, labels, sample_labels, sample_images, sample_masks):
    # Applies image cutout augmentation https://arxiv.org/abs/1708.04552
    h, w = image.shape[:2]

    # create random masks
    scales = [0.75] * 2 + [0.5] * 4 + [0.25] * 4 + [0.125] * 4 + [0.0625] * 6  # image size fraction
    for s in scales:
        if random.random() < 0.2:
            continue
        mask_h = random.randint(1, int(h * s))
        mask_w = random.randint(1, int(w * s))

        # box
        xmin = max(0, random.randint(0, w) - mask_w // 2)
        ymin = max(0, random.randint(0, h) - mask_h // 2)
        xmax = min(w, xmin + mask_w)
        ymax = min(h, ymin + mask_h)   
        
        box = np.array([xmin, ymin, xmax, ymax], dtype=np.float32)
        if len(labels):
            ioa = bbox_ioa(box, labels[:, 1:5])  # intersection over area     
        else:
            ioa = np.zeros(1)
        
        if (ioa < 0.30).all() and len(sample_labels) and (xmax > xmin+20) and (ymax > ymin+20):  # allow 30% obscuration of existing labels
            sel_ind = random.randint(0, len(sample_labels)-1)
            #print(len(sample_labels))
            #print(sel_ind)
            #print((xmax-xmin, ymax-ymin))
            #print(image[ymin:ymax, xmin:xmax].shape)
            #print([[sample_labels[sel_ind], *box]])
            #print(labels.shape)
            hs, ws, cs = sample_images[sel_ind].shape
            r_scale = min((ymax-ymin)/hs, (xmax-xmin)/ws)
            r_w = int(ws*r_scale)
            r_h = int(hs*r_scale)
            
            if (r_w > 10) and (r_h > 10):
                r_mask = cv2.resize(sample_masks[sel_ind], (r_w, r_h))
                r_image = cv2.resize(sample_images[sel_ind], (r_w, r_h))
                temp_crop = image[ymin:ymin+r_h, xmin:xmin+r_w]
                m_ind = r_mask > 0
                if m_ind.astype(np.int).sum() > 60:
                    temp_crop[m_ind] = r_image[m_ind]
                    #print(sample_labels[sel_ind])
                    #print(sample_images[sel_ind].shape)
                    #print(temp_crop.shape)
                    box = np.array([xmin, ymin, xmin+r_w, ymin+r_h], dtype=np.float32)
                    if len(labels):
                        labels = np.concatenate((labels, [[sample_labels[sel_ind], *box]]), 0)
                    else:
                        labels = np.array([[sample_labels[sel_ind], *box]])
                              
                    image[ymin:ymin+r_h, xmin:xmin+r_w] = temp_crop

    return labels

class Albumentations:
    # YOLOv5 Albumentations class (optional, only used if package is installed)
    def __init__(self):
        self.transform = None
        import albumentations as A

        self.transform = A.Compose([
            A.CLAHE(p=0.01),
            A.RandomBrightnessContrast(brightness_limit=0.2, contrast_limit=0.2, p=0.01),
            A.RandomGamma(gamma_limit=[80, 120], p=0.01),
            A.Blur(p=0.01),
            A.MedianBlur(p=0.01),
            A.ToGray(p=0.01),
            A.ImageCompression(quality_lower=75, p=0.01),],
            bbox_params=A.BboxParams(format='pascal_voc', label_fields=['class_labels']))

            #logging.info(colorstr('albumentations: ') + ', '.join(f'{x}' for x in self.transform.transforms if x.p))

    def __call__(self, im, labels, p=1.0):
        if self.transform and random.random() < p:
            new = self.transform(image=im, bboxes=labels[:, 1:], class_labels=labels[:, 0])  # transformed
            im, labels = new['image'], np.array([[c, *b] for c, b in zip(new['class_labels'], new['bboxes'])])
        return im, labels


def create_folder(path='./new'):
    # Create folder
    if os.path.exists(path):
        shutil.rmtree(path)  # delete output folder
    os.makedirs(path)  # make new output folder


def flatten_recursive(path='../coco'):
    # Flatten a recursive directory by bringing all files to top level
    new_path = Path(path + '_flat')
    create_folder(new_path)
    for file in tqdm(glob.glob(str(Path(path)) + '/**/*.*', recursive=True)):
        shutil.copyfile(file, new_path / Path(file).name)


def extract_boxes(path='../coco/'):  # from utils.datasets import *; extract_boxes('../coco128')
    # Convert detection dataset into classification dataset, with one directory per class

    path = Path(path)  # images dir
    shutil.rmtree(path / 'classifier') if (path / 'classifier').is_dir() else None  # remove existing
    files = list(path.rglob('*.*'))
    n = len(files)  # number of files
    for im_file in tqdm(files, total=n):
        if im_file.suffix[1:] in img_formats:
            # image
            im = cv2.imread(str(im_file))[..., ::-1]  # BGR to RGB
            h, w = im.shape[:2]

            # labels
            lb_file = Path(img2label_paths([str(im_file)])[0])
            if Path(lb_file).exists():
                with open(lb_file, 'r') as f:
                    lb = np.array([x.split() for x in f.read().strip().splitlines()], dtype=np.float32)  # labels

                for j, x in enumerate(lb):
                    c = int(x[0])  # class
                    f = (path / 'classifier') / f'{c}' / f'{path.stem}_{im_file.stem}_{j}.jpg'  # new filename
                    if not f.parent.is_dir():
                        f.parent.mkdir(parents=True)

                    b = x[1:] * [w, h, w, h]  # box
                    # b[2:] = b[2:].max()  # rectangle to square
                    b[2:] = b[2:] * 1.2 + 3  # pad
                    b = xywh2xyxy(b.reshape(-1, 4)).ravel().astype(np.int)

                    b[[0, 2]] = np.clip(b[[0, 2]], 0, w)  # clip boxes outside of image
                    b[[1, 3]] = np.clip(b[[1, 3]], 0, h)
                    assert cv2.imwrite(str(f), im[b[1]:b[3], b[0]:b[2]]), f'box failure in {f}'


def autosplit(path='../coco', weights=(0.9, 0.1, 0.0), annotated_only=False):
    """ Autosplit a dataset into train/val/test splits and save path/autosplit_*.txt files
    Usage: from utils.datasets import *; autosplit('../coco')
    Arguments
        path:           Path to images directory
        weights:        Train, val, test weights (list)
        annotated_only: Only use images with an annotated txt file
    """
    path = Path(path)  # images dir
    files = sum([list(path.rglob(f"*.{img_ext}")) for img_ext in img_formats], [])  # image files only
    n = len(files)  # number of files
    indices = random.choices([0, 1, 2], weights=weights, k=n)  # assign each image to a split

    txt = ['autosplit_train.txt', 'autosplit_val.txt', 'autosplit_test.txt']  # 3 txt files
    [(path / x).unlink() for x in txt if (path / x).exists()]  # remove existing

    print(f'Autosplitting images from {path}' + ', using *.txt labeled images only' * annotated_only)
    for i, img in tqdm(zip(indices, files), total=n):
        if not annotated_only or Path(img2label_paths([str(img)])[0]).exists():  # check label
            with open(path / txt[i], 'a') as f:
                f.write(str(img) + '\n')  # add image to txt file
    
    
def load_segmentations(self, index):
    key = '/work/handsomejw66/coco17/' + self.img_files[index]
    #print(key)
    # /work/handsomejw66/coco17/
    return self.segs[key]