精读yolo LoadImagesAndLabels类-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_27172615/article/details/128729070

该文详细介绍了如何使用albumentations库进行图像增强，包括安装、配置清华源、读取文件路径、标签处理、缓存管理和数据增强方法如Mosaic和MixUp等。同时，文章还提到了数据预处理过程中的各种变换，如旋转、平移、缩放等。

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安装albumentations

配置清华源
pip config set global.index-url https://pypi.tuna.tsinghua.edu.cn/simple

pip install -U albumentations

安装不起的问题一般都是网络的问题，开源地址：

GitHub - albumentations-team/albumentations: Fast image augmentation library and an easy-to-use wrapper around other libraries. Documentation: https://albumentations.ai/docs/ Paper about the library: https://www.mdpi.com/2078-2489/11/2/125

初始化：

文件读取：

        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) as t:
                        t = t.read().strip().splitlines()
                        parent = str(p.parent) + os.sep
                        f += [x.replace('./', parent, 1) if x.startswith('./') else x for x in t]  # to global path
                        # f += [p.parent / x.lstrip(os.sep) for x in t]  # to global path (pathlib)
                else:
                    raise FileNotFoundError(f'{prefix}{p} does not exist')
            self.im_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.im_files, f'{prefix}No images found'
        except Exception as e:
            raise Exception(f'{prefix}Error loading data from {path}: {e}\n{HELP_URL}') from e

测试一下：

if __name__ == '__main__':
    path = 'D:\PycharmProjects\opencvtest\datasets\coco\images'
    a = LoadImagesAndLabels(path)
    next(iter(a))

它把根目录的所有地址都读取出来了。关键这句代码

f += glob.glob(str(p / '**' / '*.*'), recursive=True)

即使不了解通配符匹配规则，大概也知道是什么意思了。 **表示所有文件名， *.*表示所有文件名。p 传入的根目录

缓存cahe

        # Check cache
        self.label_files = img2label_paths(self.im_files)  # labels
        cache_path = (p if p.is_file() else Path(self.label_files[0]).parent).with_suffix('.cache')
        try:
            cache, exists = np.load(cache_path, allow_pickle=True).item(), True  # load dict
            assert cache['version'] == self.cache_version  # matches current version
            assert cache['hash'] == get_hash(self.label_files + self.im_files)  # identical hash
        except Exception:
            cache, exists = self.cache_labels(cache_path, prefix), False  # run cache ops

发现了结果不一样，先不管看这个方法

def img2label_paths(img_paths):
    # Define label paths as a function of image paths
    sa, sb = f'{os.sep}images{os.sep}', f'{os.sep}labels{os.sep}'  # /images/, /labels/ substrings
    return [sb.join(x.rsplit(sa, 1)).rsplit('.', 1)[0] + '.txt