运行python evaluate.py测试自己的数据集时出现如下错误：
mxnet.base.MXNetError: [15:44:10] src/operator/tensor/./…/elemwise_op_common.h:123: Check failed: assign(&dattr, (*vec)[i]) Incompatible attr in node at 0-th output: expected [18], got [126]
因为没有改evaluate.py的参数class_name和num_class，需要改成自己的数据集相关的class_name和num_class.