Why raise error "cannot infer num_classes when target is all zero" in accuracy metric
Why does the accuracy metric raise error when target is all zero?
(https://github.com/PyTorchLightning/pytorch-lightning/blob/0.8.1/pytorch_lightning/metrics/functional/classification.py#L222)
I think it's still reasonable to compute accuracy even when the target in the minibatch happens to be all zero.