
  mutate(train_set = map(splits, training)) %&gt;% 
* unnest(train_set)
## # A tibble: 2,198 x 83
##    splits id    MS_SubClass MS_Zoning Lot_Frontage Lot_Area Street Alley
##    &lt;list&gt; &lt;chr&gt; &lt;fct&gt;       &lt;fct&gt;            &lt;dbl&gt;    &lt;int&gt; &lt;fct&gt;  &lt;fct&gt;
##  1 &lt;spli‚Ä¶ trai‚Ä¶ One_Story_‚Ä¶ Resident‚Ä¶           81    14267 Pave   No_A‚Ä¶
##  2 &lt;spli‚Ä¶ trai‚Ä¶ Two_Story_‚Ä¶ Resident‚Ä¶           74    13830 Pave   No_A‚