It is supposed to be compatible for relative path in val2017.txt

[ckmessi]

Problem

When I run the basic demo script:

python test_half.py --data coco2017.data --cfg cfg/yolov4-pacsp.cfg --weights weights/yolov4-pacsp.pt --img 736 --iou-thr 0.7 --batch-size 8

It raised exception that the label files had not been found:

Traceback (most recent call last):
  File "test_half.py", line 257, in <module>
    opt.augment)
  File "test_half.py", line 64, in test
    dataset = LoadImagesAndLabels(path, img_size, batch_size, rect=True, single_cls=opt.single_cls)
  File "/path/to/PyTorch_YOLOv4/utils/datasets.py", line 382, in __init__
    assert nf > 0, 'No labels found in %s. See %s' % (os.path.dirname(file) + os.sep, help_url)
AssertionError: No labels found in ./labels/val2017/. See https://github.com/ultralytics/yolov3/wiki/Train-Custom-Data

By diving into the problem, I found it was caused by relative path.
For the coco2017 dataset, the zip file coco2017labels.zip download from data/get_coco2017.sh contains files:

- coco/
    - annotations/
    - images/
    - labels/
    - train2017.txt
    - val2017.txt
    - ...

The content of val2017.txt is like this:

./images/val2017/000000182611.jpg
./images/val2017/000000335177.jpg
./images/val2017/000000278705.jpg
./images/val2017/000000463618.jpg
./images/val2017/000000568981.jpg
...

Here, the paths of images are relative, so the script could not find the label file.

Solution

Refered to Yolov5 project, we can add two line in utils/database.py to support the relative path:

self.img_files = [x.replace('./', parent) if x.startswith('./') else x for x in self.img_files]

I have create a pull request #32

[FYM1209]

this two line add where