在用caret做特征选取的时候出现以下问题:
Error in { :
  task 1 failed - "task 1 failed - "At least one of the class levels is not a valid R variable name; This will cause errors when class probabilities are generated because the variables names will be converted to  X1, X2, X3 .

什么覆盖问题，完全没思路啊..

我的代码:
数据在附件.