Does mxnet symbol has IoU loss? or I need to implement it by my self?

Does mxnet symbol has IoU loss? or I need to implement it by my self?
Any advice will be appreciated, thanks.

afaik there is no iou loss in symbol. you’ll have to implement it yourself and you can follow this answer as a guide on how to create a custom symbol loss: https://stackoverflow.com/questions/45809154/mxnet-custom-loss-function-and-eval-metric

thanks for your reply. My problem is that I do not know how to write the backward function.
Any advice will be appreciated, thanks