TypeError: object of type 'DataContainer' has no len()

I installed the Docker image as mentioned in install.md and then tried testing the Faster RCNN model using the instructions provided in Getting_started.md

I ran the following code

python tools/test.py configs/faster_rcnn_r50_fpn_1x.py checkpoints/faster_rcnn_r50_fpn_1x_20181010-3d1b3351.pth --show

I got the following output

loading annotations into memory...
Done (t=0.59s)
creating index...
index created!
[                                                  ] 0/5000, elapsed: 0s, ETA:Traceback (most recent call last):
  File "tools/test.py", line 224, in <module>
    main()
  File "tools/test.py", line 184, in main
    outputs = single_gpu_test(model, data_loader, args.show)
  File "tools/test.py", line 26, in single_gpu_test
    result = model(return_loss=False, rescale=not show, **data)
  File "/opt/conda/lib/python3.6/site-packages/torch/nn/modules/module.py", line 493, in __call__
    result = self.forward(*input, **kwargs)
  File "/opt/conda/lib/python3.6/site-packages/torch/nn/parallel/data_parallel.py", line 140, in forward
    return self.module(*inputs, **kwargs)
  File "/opt/conda/lib/python3.6/site-packages/torch/nn/modules/module.py", line 493, in __call__
    result = self.forward(*input, **kwargs)
  File "/mmdetection/mmdet/core/fp16/decorators.py", line 49, in new_func
    return old_func(*args, **kwargs)
  File "/mmdetection/mmdet/models/detectors/base.py", line 88, in forward
    return self.forward_test(img, img_meta, **kwargs)
  File "/mmdetection/mmdet/models/detectors/base.py", line 79, in forward_test
    return self.simple_test(imgs[0], img_metas[0], **kwargs)
  File "/mmdetection/mmdet/models/detectors/two_stage.py", line 231, in simple_test
    x, img_meta, self.test_cfg.rpn) if proposals is None else proposals
  File "/mmdetection/mmdet/models/detectors/test_mixins.py", line 10, in simple_test_rpn
    proposal_list = self.rpn_head.get_bboxes(*proposal_inputs)
  File "/mmdetection/mmdet/core/fp16/decorators.py", line 127, in new_func
    return old_func(*args, **kwargs)
  File "/mmdetection/mmdet/models/anchor_heads/anchor_head.py", line 216, in get_bboxes
    for img_id in range(len(img_metas)):
TypeError: object of type 'DataContainer' has no len()

I have downloaded the checkpoint file and saved it in the checkpoints folder as mentioned above. I have also downloaded the COCO data and placed it in the directory as instructed in install.md

I am not able to understand the exact reason of the error. What I can say is that this term is causing the error,

len(img_metas)

So I just printed the object right before where the error is caused

print(img_metas)

and I got the output

DataContainer([[{'filename': 'data/coco/val2017/000000397133.jpg', 'ori_shape': (427, 640, 3), 'img_shape': (800, 1199, 3), 'pad_shape': (800, 1216, 3), 'scale_factor': 1.873536299765808, 'flip': False, 'img_norm_cfg': {'mean': array([123.675, 116.28 , 103.53 ], dtype=float32), 'std': array([58.395, 57.12 , 57.375], dtype=float32), 'to_rgb': True}}]])

if this helps in any way.

Please help me understand the error. Thank you

[Yang-Parky]

I have the same problem, and I solved it. just update mmcv to the latest version. pip uninstall mmcv-full pip install mmcv-full

modify mmdet/__init__.py mmcv_maximum_version = '1.3.6'

Perfect~

[wpc2333]

I have the same problem, and I solved it. just update mmcv to the latest version. pip uninstall mmcv-full pip install mmcv-full

modify mmdet/__init__.py mmcv_maximum_version = '1.3.6'