R Caret：种子和createMultiFolds

Question

我想使代码可重复，并在循环中使用seeds参数和createMultiFolds。

我设置了以下代码：

cv_model <- function(dat, targets){

  library(randomForest)
  library(caret)
  library(MLmetrics)
  library(Metrics)

  results <<- list(weight = NA, vari = NA)

  # set up error measures
  sumfct <- function(data, lev = NULL, model = NULL){
    mape <- MLmetrics::MAPE(y_pred = data$pred, y_true = data$obs)
    RMSE <- sqrt(mean((data$pred - data$obs)^2, na.omit = TRUE))
    c(MAPE = mape, RMSE = RMSE)
  }

  for (i in 1:length(targets)) {

    set.seed(43)
    folds <- caret::createMultiFolds(y = dat$weight,
                                     k = 3,
                                     times = 3)

    set.seed(43)
    myseeds <- vector(mode = "list", length = 3*3+1)
    for (i in 1:9) {
      myseeds[[i]] <- sample.int(n=1000, 1)
    }
    # for the final model
    myseeds[[10]] <- sample.int(n=1000, 1)

    # specifiy trainControl
    control <- caret::trainControl(method="repeatedcv", number=3, repeats=3, search="grid", 
                                   savePred =T,
                                   summaryFunction = sumfct, index = folds, seeds = myseeds)
    # fixed mtry
    params <- data.frame(mtry = 2)

    # choose predictor columns by excluding target columns
    preds <- dat[, -c(which(names(dat) == "Time"),
                      which(names(dat) == "Chick"),
                      which(names(dat) == "Diet"))]

    # set target variables
    response <- dat[, which(names(dat) == targets[i])]

    set.seed(42)
    model <- caret::train(x = preds,
                          y = response,
                          data = dat,
                          method="rf",
                          ntree = 25, 
                          metric= "RMSE", 
                          tuneGrid=params, 
                          trControl=control)

    results[[i]] <<- model

  }
}

targets <- c("weight", "vari")
dat <- as.data.frame(ChickWeight)
# generate random numbers
set.seed(1)
dat$vari <- c(runif(nrow(dat))) 

## use 2 of the cores
library(doParallel)
cl <- makePSOCKcluster(2)
registerDoParallel(cl)
# use function
cv_model(dat = dat, targets = targets)

# end parallel computing
stopCluster(cl)
# unregister doParallel by registering DoSeq (do sequential)
registerDoSEQ()

运行代码后，出现错误消息Error: Please make sure 'y' is a factor or numeric value..。

如果删除以下几行

    set.seed(43)
    myseeds <- vector(mode = "list", length = 3*3+1)
    for (i in 1:9) {
      myseeds[[i]] <- sample.int(n=1000, 1)
    }
    # for the final model
    myseeds[[10]] <- sample.int(n=1000, 1)    

在trainControl , seeds = myseeds中，然后代码运行而没有错误消息。

如何解决该错误，同时在代码中提供seeds和createMultiFolds？