你遇到下面的问题了吗？，
> rfFit <- train(CARAVAN~.,data = trainingInd,
+                method = 'rf',
+                trControl = ctrl,
+                ntree = 1500,
+                tuneLength =5,
+                metric = 'ROC')
Error: 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  X2, X1 . Please use factor levels that can be used as valid R variable names  (see ?make.names for help).

谢谢分享