将列转换为数据框列表中的因子 [英] converting columns to factor over list of dataframes

问题描述

我正在尝试将数据帧列表中的几列转换为因子.我已经尝试过了，但是似乎没有将列转换为因子:

I'm trying to convert several columns in a list of dataframes into factors. I've tried this, but it doesn't seem to convert the columns into factors:

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)
}

关于如何解决此问题的任何想法?

Any ideas on how to fix this?

推荐答案

让我知道我是否正确理解

Let me know if I understood correctly

#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" 

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