在动态图下 nms 出来的 pred_boxes.shape 是 [N, 6] 但静态图就变为了 [N, 1] 导致报错

bbox_pred, bbox_num, _ = self.nms(pred_boxes, pred_scores)

if bbox_pred.shape[0] == 0:
    pred_result =  paddle.to_tensor(np.array([[-1, 0.0, 0.0, 0.0, 0.0, 0.0]], dtype='float32'))
    bbox_num = paddle.to_tensor(np.array([1], dtype='int32'))

    return pred_result, bbox_num

print("bbox_pred", bbox_pred.shape)

pred_label = bbox_pred[:, 0:1]
pred_score = bbox_pred[:, 1:2]
pred_bbox = bbox_pred[:, 2:]
keep_mask = nonempty_bbox(pred_bbox, return_mask=True)
keep_mask = paddle.unsqueeze(keep_mask, [1])
pred_label = paddle.where(keep_mask, pred_label,
                          paddle.ones_like(pred_label) * -1)

pred_result = paddle.concat([pred_label, pred_score, pred_bbox], axis=1)

return pred_result, bbox_num

# 部分打印如下

bbox_pred
(-1, 1)
Traceback (most recent call last):
  File "tools/export_model.py", line 114, in <module>
    main()
  File "tools/export_model.py", line 110, in main
    run(FLAGS, cfg)
  File "tools/export_model.py", line 78, in run
.....
    File "/home/aistudio/ppdet/modeling/architectures/meta_arch.py", line 28, in forward
	out = self.get_pred()
    File "/home/aistudio/ppdet/modeling/architectures/retinanet.py", line 84, in get_pred
	bbox_pred, bbox_num = self._forward()
    File "/home/aistudio/ppdet/modeling/architectures/retinanet.py", line 66, in _forward
	self.inputs
    File "/home/aistudio/ppdet/modeling/post_process.py", line 769, in __call__
        pred_label = bbox_pred[:, 0:1]
        pred_score = bbox_pred[:, 1:2]
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <--- HERE
        pred_bbox = bbox_pred[:, 2:]
        keep_mask = nonempty_bbox(pred_bbox, return_mask=True)

    File "/opt/conda/envs/python35-paddle120-env/lib/python3.7/site-packages/paddle/fluid/framework.py", line 1783, in __getitem__
	return _getitem_impl_(self, item)
    File "/opt/conda/envs/python35-paddle120-env/lib/python3.7/site-packages/paddle/fluid/variable_index.py", line 463, in _getitem_impl_
	attrs=attrs)
    File "/opt/conda/envs/python35-paddle120-env/lib/python3.7/site-packages/paddle/fluid/framework.py", line 3184, in append_op
	attrs=kwargs.get("attrs", None))
    File "/opt/conda/envs/python35-paddle120-env/lib/python3.7/site-packages/paddle/fluid/framework.py", line 2344, in __init__
	self.desc.infer_shape(self.block.desc)

    ValueError: (InvalidArgument) When step > 0, end should be greater than start, but received end = 1, start = 1.
  [Hint: Expected end > start, but received end:1 <= start:1.] (at /paddle/paddle/fluid/operators/slice_utils.h:59)
  [operator < slice > error]