Created by: lxk767363331

在seg中设置动态权重中有这样一段代码，weight / fluid.layers.reduce_sum(weight)已经得到各个比例的权重了，，不理解为什么要*num_classes，望解答 谢谢

https://github.com/PaddlePaddle/PaddleSeg/blob/4bc70d817d5fb448ee26db39bd3e321b13c08052/pdseg/loss.py#L61

weight = weight / fluid.layers.reduce_sum(weight) * num_classes