title: Data transformation with the package "bestNormalize" on a list with multiple dataframes
body: <p>I would like to transform my data but I am not quite sure which method is the best one. Thus, I use the package &quot;bestNormalize&quot;.</p>
  <p>It works fine on one single column of a dataframe, however I have have list with two dataframes (each dataframe with 9 columns) and I would like to apply the function &quot;bestNormalize&quot; to each column. I tried to map but it does not work.</p>
  <p>Further, I would like to apply other functions (transformation of the data, e.g. with the function &quot;yeojohnson&quot;) of the package in the same how I applied the &quot;bestNormalize&quot; function to each column of each dataframe.</p>
  <p>Does anybody know how this works? Thanks in advance.</p>
  <pre><code>
  install.packages(&quot;bestNormalize&quot;)
  library(bestNormalize)
  
  install.packages(&quot;purrr&quot;)
  library(purrr)
  
  # Data
  a &lt;- data.frame(
    met1 = rnorm(n = 100, mean = 0, sd = 1),
    met2 = rnorm(n = 100, mean = 0, sd = 1),
    met3 = rnorm(n = 100, mean = 0, sd = 1),
    met4 = rnorm(n = 100, mean = 0, sd = 1),
    met5 = rnorm(n = 100, mean = 0, sd = 1),
    met6 = rnorm(n = 100, mean = 0, sd = 1),
    met7 = rnorm(n = 100, mean = 0, sd = 1),
    met8 = rnorm(n = 100, mean = 0, sd = 1),
    met9 = rnorm(n = 100, mean = 0, sd = 1)
  )
  
  
  y &lt;- data.frame(
    met1 = rnorm(n = 100, mean = 0, sd = 1),
    met2 = rnorm(n = 100, mean = 0, sd = 1),
    met3 = rnorm(n = 100, mean = 0, sd = 1),
    met4 = rnorm(n = 100, mean = 0, sd = 1),
    met5 = rnorm(n = 100, mean = 0, sd = 1),
    met6 = rnorm(n = 100, mean = 0, sd = 1),
    met7 = rnorm(n = 100, mean = 0, sd = 1),
    met8 = rnorm(n = 100, mean = 0, sd = 1),
    met9 = rnorm(n = 100, mean = 0, sd = 1)
  )
  
  
  my_list &lt;- list(a, y)
   
  # Works:
  bestNormalize::bestNormalize(my_list[[1]]$met1)
  
  # Does not work:
  stand_dat_men &lt;- my_list  %&gt;% purrr::map(~mutate_at(.x, .vars = vars(met1:met9), ~bestNormalize(.)))
  
  
  
  
  
  </code></pre>