使用caretEnsemble包中的trainControl和train函数训练模型，使用的数据集为标签为label的分类数据，代码如下：

control <- trainControl(method="repeatedcv", number=5, repeats=1, savePredictions=TRUE, classProbs=TRUE)
rf<- train(label ~ ., data = train_data, 
                 method = "rf", 
                 trControl = control)
rf

运行后发生错误

In addition: Warning messages:
1: In train.default(x, y, weights = w, ...) :
You are trying to do regression and your outcome only has two possible values Are you trying to do classification? If so, use a 2 level factor as your outcome column.
2: In train.default(x, y, weights = w, ...) :
cannnot compute class probabilities for regression

解决方法：将数据集标签列的数据由0，1改为yes,no，数值类型的数据被R默认是做回归，改为两种类别的字符即可继续运行。