yolov5已跑通 训练数据更改xml的类名后 类别溢出的错误 出现A

AssertionError: Label class 4.0 exceeds nc=3 in Possible class labels are 0-2
错误如下：

Traceback (most recent call last):
  File "train.py", line 589, in <module>
    main(opt)
  File "train.py", line 488, in main
    train(opt.hyp, opt, device)
  File "train.py", line 206, in train
    assert mlc < nc, f'Label class {mlc} exceeds nc={nc} in {data}. Possible class labels are 0-{nc - 1}'
AssertionError: Label class 4.0 exceeds nc=3 in E:/code/yolov5-master/Helmet.yaml. Possible class labels are 0-2

我分了三类 也检查过标签中没有多余的类别

你的标签类别和yaml里面的nc对不上，报错的意思是你的标签里面的标签数目是4种，标签下标是从0开始的，你要么标签错误，要么类别数目不对。