return [self.imgs[id] for id in ids] KeyError: ‘0’

使用DETR读取自己转的COCO格式数据集的时候，出现错误：

loading annotations into memory...
Done (t=0.06s)
creating index...
index created!
loading annotations into memory...
Done (t=0.02s)
creating index...
index created!
Start training
Error idx: 1914
Error idx: 3631
Error idx: 6603
Error idx: 3612
Error idx: 1286
Error idx: 4989
Error idx: 6612
Error idx: 496
Error idx: 4437
Error idx: 3876
Error idx: 5219
Error idx: 1750
Error idx: 2127
Error idx: 2016
Error idx: 5546
Error idx: 3429
Error idx: 3592
Error idx: 4294
Traceback (most recent call last):
  File "main.py", line 443, in <module>
Error idx: 3040
    main(args)
  File "main.py", line 369, in main
Error idx: 5061
    train_stats = train_one_epoch(
  File "/home/ubuntu/bigdisk/part4/DETR/engine.py", line 42, in train_one_epoch
    for samples, targets in metric_logger.log_every(data_loader, print_freq, header, logger=logger):
  File "/home/ubuntu/bigdisk/part4/DETR/util/misc.py", line 238, in log_every
    for obj in iterable:
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/torch/utils/data/dataloader.py", line 521, in __next__
Error idx: 4740
    data = self._next_data()
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/torch/utils/data/dataloader.py", line 1203, in _next_data
    return self._process_data(data)
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/torch/utils/data/dataloader.py", line 1229, in _process_data
    data.reraise()
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/torch/_utils.py", line 425, in reraise
    raise self.exc_type(msg)
KeyError: Caught KeyError in DataLoader worker process 0.
Original Traceback (most recent call last):
  File "/home/ubuntu/bigdisk/part4/DETR/datasets/coco.py", line 44, in __getitem__
    img, target = super(CocoDetection, self).__getitem__(idx)
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/torchvision/datasets/coco.py", line 45, in __getitem__
    image = self._load_image(id)
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/torchvision/datasets/coco.py", line 37, in _load_image
    path = self.coco.loadImgs(id)[0]["file_name"]
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/pycocotools/coco.py", line 229, in loadImgs
    return [self.imgs[id] for id in ids]
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/pycocotools/coco.py", line 229, in <listcomp>
    return [self.imgs[id] for id in ids]
KeyError: '0'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/torch/utils/data/_utils/worker.py", line 287, in _worker_loop
    data = fetcher.fetch(index)
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/torch/utils/data/_utils/fetch.py", line 44, in fetch
    data = [self.dataset[idx] for idx in possibly_batched_index]
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/torch/utils/data/_utils/fetch.py", line 44, in <listcomp>
    data = [self.dataset[idx] for idx in possibly_batched_index]
  File "/home/ubuntu/bigdisk/part4/DETR/datasets/coco.py", line 48, in __getitem__
    img, target = super(CocoDetection, self).__getitem__(idx)
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/torchvision/datasets/coco.py", line 45, in __getitem__
    image = self._load_image(id)
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/torchvision/datasets/coco.py", line 37, in _load_image
    path = self.coco.loadImgs(id)[0]["file_name"]
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/pycocotools/coco.py", line 229, in loadImgs
    return [self.imgs[id] for id in ids]
  File "/home/ubuntu/anaconda3/envs/DETR/lib/python3.8/site-packages/pycocotools/coco.py", line 229, in <listcomp>
    return [self.imgs[id] for id in ids]
KeyError: '0'

原因是image_id包含非数字或编号从0开始，例如00824这种。

所以，只需要改一下image_id即可。