t_1</code>, <code>pcnt_2</code>, the percentage of total memory usage of each column within 
  each of <code>df1</code> and <code>df2</code>.</p></li>
</ul><p>For a <strong>grouped dataframe</strong>, the tibble returned is as for a single dataframe, but where 
the first <code>k</code> columns are the grouping columns.  There will be as many rows in the result 
as there are unique combinations of the grouping variables.</p>
    </div>
    <div id="see-also">
    <h2>See also</h2>
    <div class="dont-index"