R 将列转换为数据帧列表上的系数

我试图将数据帧列表中的几列转换为因子。 我尝试过这个方法，但它似乎无法将列转换为因子：

factor_cols_REx <- c('GESLACHT','GEVKL','BEROEP')
for (i in (1:9)) {
  dataset_RE10_2014[[i]] <- lapply(dataset_RE10_2014[[i]][factor_cols_REx],factor)
  dataset_RE10_2015[[i]] <- lapply(dataset_RE10_2015[[i]][factor_cols_REx],factor)
}

---

factor\u cols\u REx我们需要在
的左侧和右侧有相同的子集，如果我理解正确，请告诉我

#DATA
dat = list(A = mtcars, B = mtcars)
#Columns we want to convert to factor
factor_cols = c("mpg", "hp")

#Go through the list using lapply and change specific columns to factor in each sub-group
#Modified from https://stackoverflow.com/a/33180265/7128934
dat2 = lapply(dat, function(x){
     x[factor_cols] = lapply(x[factor_cols], factor)
     x
    })

#Check class in output list
lapply(dat2, function(x) sapply(x, class))
#$A
#      mpg       cyl      disp        hp      drat        wt      qsec        vs        am      gear      carb 
# "factor" "numeric" "numeric"  "factor" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" 

#$B
#      mpg       cyl      disp        hp      drat        wt      qsec        vs        am      gear      carb 
# "factor" "numeric" "numeric"  "factor" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" 

#Check class in input list
lapply(dat, function(x) sapply(x, class))
#$A
#      mpg       cyl      disp        hp      drat        wt      qsec        vs        am      gear      carb 
#"numeric" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" 

#$B
#      mpg       cyl      disp        hp      drat        wt      qsec        vs        am      gear      carb 
#"numeric" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" "numeric" 

使用
dplyr
和
purrr

library(dplyr)
library(purrr) 

factor_cols_REx <- c('GESLACHT','GEVKL','BEROEP')

dataset_RE10_2014 <- map(dataset_RE10_2014, ~mutate_at(.x, factor_cols_REx, factor))

dataset_RE10_2015 <- map(dataset_RE10_2015, ~mutate_at(.x, factor_cols_REx, factor))

库（dplyr）
图书馆（purrr）
你能更准确地解释一下吗？谢谢你的解决方案，它们都有效！
library(dplyr)
library(purrr) 

factor_cols_REx <- c('GESLACHT','GEVKL','BEROEP')

dataset_RE10_2014 <- map(dataset_RE10_2014, ~mutate_at(.x, factor_cols_REx, factor))

dataset_RE10_2015 <- map(dataset_RE10_2015, ~mutate_at(.x, factor_cols_REx, factor))