title: convert similarly named unequally length list elements to data frame R
body: <p>I know theres so many list to dataframe questions but I cant find the solution to this easy problem. Lets say I have:</p>
  
  <pre><code>library(tidyverse)
  library(janitor)
  df &lt;- data.frame( group = c(rep("A",3), rep("B", 6)),
                    test_value = c(0,1,2, 0,1,2,3,4,5))
  df_list &lt;- df %&gt;% 
    split(.$group) %&gt;% 
    map(~tabyl(.x$test_value))
  df_list  
  # $A
  #  .x$test_value n   percent
  #              0 1 0.3333333
  #              1 1 0.3333333
  #              2 1 0.3333333
  
  # $B
  #  .x$test_value n   percent
  #              0 1 0.1666667
  #              1 1 0.1666667
  #              2 1 0.1666667
  #              3 1 0.1666667
  #              4 1 0.1666667
  #              5 1 0.1666667
  </code></pre>
  
  <p>All I want to do is convert it to this named dataframe of the following:</p>
  
  <pre><code>  A_test_value   A_n A_percent B_test_value   B_n B_percent
           &lt;dbl&gt; &lt;dbl&gt;     &lt;dbl&gt;        &lt;dbl&gt; &lt;dbl&gt;     &lt;dbl&gt;
  1            0     1     0.333            0     1     0.167
  2            1     1     0.333            1     1     0.167
  3            2     1     0.333            2     1     0.167
  4           NA    NA    NA                3     1     0.167
  5           NA    NA    NA                4     1     0.167
  6           NA    NA    NA                5     1     0.167
  </code></pre>
  
  <p>I've seen this but it is slightly different (<a href="https://stackoverflow.com/questions/27153979/converting-nested-list-unequal-length-to-data-frame">Converting nested list (unequal length) to data frame</a>)</p>
  
  <p>Would anyone have a quick solution (maybe <code>dplyr</code> type) please?</p>