YOLOv5 分类模型 数据集加载

flyfish

数据集的加载 python实现，不使用torch库
简化实现

import os
import os.path
from typing import Any, Callable, cast, Dict, List, Optional, Tuple, Union


class DatasetFolder:

    def __init__(
        self,
        root: str,

    ) -> None:
        self.root=root
        classes, class_to_idx = self.find_classes(self.root)
        samples = self.make_dataset(self.root, class_to_idx)
        
        self.classes = classes
        self.class_to_idx = class_to_idx
        self.samples = samples
        self.targets = [s[1] for s in samples]


    @staticmethod
    def make_dataset(
        directory: str,
        class_to_idx: Optional[Dict[str, int]] = None,

    ) -> List[Tuple[str, int]]:
 
        directory = os.path.expanduser(directory)

        if class_to_idx is None:
            _, class_to_idx = self.find_classes(directory)
        elif not class_to_idx:
            raise ValueError("'class_to_index' must have at least one entry to collect any samples.")



        instances = []
        available_classes = set()
        for target_class in sorted(class_to_idx.keys()):
            class_index = class_to_idx[target_class]
            target_dir = os.path.join(directory, target_class)
            if not os.path.isdir(target_dir):
                continue
            for root, _, fnames in sorted(os.walk(target_dir, followlinks=True)):
                for fname in sorted(fnames):
                    path = os.path.join(root, fname)
                    if 1:#验证:
                        item = path, class_index
                        instances.append(item)

                        if target_class not in available_classes:
                            available_classes.add(target_class)

        empty_classes = set(class_to_idx.keys()) - available_classes
        if empty_classes:
            msg = f"Found no valid file for the classes {', '.join(sorted(empty_classes))}. "


        return instances

    def find_classes(self, directory: str) -> Tuple[List[str], Dict[str, int]]:
 
        classes = sorted(entry.name for entry in os.scandir(directory) if entry.is_dir())
        if not classes:
            raise FileNotFoundError(f"Couldn't find any class folder in {directory}.")

        class_to_idx = {cls_name: i for i, cls_name in enumerate(classes)}
        return classes, class_to_idx


    def __getitem__(self, index: int) -> Tuple[Any, Any]:

        path, target = self.samples[index]
        sample = self.loader(path)


        return sample, target

    def __len__(self) -> int:
        return len(self.samples)





dataset =  DatasetFolder(root="/media/a/flyfish/test");

print(dataset)
print("dataset.targets:",dataset.targets)
print("dataset.classes:",dataset.classes)
print("samples:",dataset.samples)

find_classes 将标签索引和标签内容对应

0,1,2是标签索引
'n01440764', 'n01443537', 'n01484850'是类别名字也是文件夹名字
按照升序排序

dataset.targets: [0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2]
dataset.classes: ['n01440764', 'n01443537', 'n01484850']

样本中一个是图像文件的绝对路径，后面的是标签

samples: [('/media/a/flyfish/test/n01440764/ILSVRC2012_val_00000293.JPEG', 0),
          ('/media/a/flyfish/test/n01440764/ILSVRC2012_val_00002138.JPEG', 0),
          ('/media/a/flyfish/test/n01440764/ILSVRC2012_val_00003014.JPEG', 0),
          ('/media/a/flyfish/test/n01440764/ILSVRC2012_val_00006697.JPEG', 0),
          ('/media/a/flyfish/test/n01443537/ILSVRC2012_val_00000236.JPEG', 1),
          ('/media/a/flyfish/test/n01443537/ILSVRC2012_val_00000262.JPEG', 1),
          ('/media/a/flyfish/test/n01443537/ILSVRC2012_val_00000307.JPEG', 1),
          ('/media/a/flyfish/test/n01443537/ILSVRC2012_val_00000994.JPEG', 1),
          ('/media/a/flyfish/test/n01484850/ILSVRC2012_val_00002338.JPEG', 2),
          ('/media/a/flyfish/test/n01484850/ILSVRC2012_val_00002752.JPEG', 2),
          ('/media/a/flyfish/test/n01484850/ILSVRC2012_val_00004311.JPEG', 2),
          ('/media/a/flyfish/test/n01484850/ILSVRC2012_val_00004329.JPEG', 2)]

可以功能丰富一些，例如检测文件的扩展名是否是支持的图像文件

IMG_EXTENSIONS = (".jpg", ".jpeg", ".png", ".ppm", ".bmp", ".pgm", ".tif", ".tiff", ".webp")

def has_file_allowed_extension(filename: str, extensions: Union[str, Tuple[str, ...]]) -> bool:
    """检查文件是否为允许的扩展名
    """
    return filename.lower().endswith(extensions if isinstance(extensions, str) else tuple(extensions))

def is_image_file(filename: str) -> bool:
    return has_file_allowed_extension(filename, IMG_EXTENSIONS)

测试

r=is_image_file("/media/a/flyfish/data/imagewoof/val/n02086240/1.jpeg");

print(r)#True

r=is_image_file("/media/a/flyfish/data/imagewoof/val/n02086240/1.txt");

print(r)#False