RandomForest功能警告

Question

当我尝试运行随机森林（用于分类）时，我会得到警告，

Warning message:
In randomForest.default(m, y, ...) :
  The response has five or fewer unique values.  Are you sure you want to do regression?

我已经用看门人包清洁了（巨大的）数据集，并试图考虑变量。有人理解为什么我仍然会发出警告吗？

data2 <- experimental_data

x = janitor::clean_names(data2)

#--------------------------------------

#Partition data
set.seed(93)
ind <- sample(2, nrow(x), replace= TRUE,prob=c(0.7,0.3))
train <- x[ind==1,]
test<- x[ind==2,]

str(train)
train[sapply(train, is.character)] <- lapply(train[sapply(train, is.character)], 
                                       as.factor)
str(train)
#Train Random forest on UCI heart dataset
rf <- randomForest(y_full~., data=train, importance=TRUE, predict.all=TRUE,proximity=TRUE)