title: how can I rbind two dataframe that has different variables
body: <p>I have a dataset that look like this:</p>
  <p><a href="https://i.stack.imgur.com/81Pee.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/81Pee.png" alt="enter image description here" /></a></p>
  <p>I would like to combine those two datasets. How can I do that. I can't use <code>rbind</code> as df has more vars.
  Sample data can be build using codes:</p>
  <pre><code>df&lt;-structure(list(ID = c(1, 2, 3), High = c(25, 36, 75), weight = c(38, 
  58, 36), date = c(1, 1, 1)), row.names = c(NA, -3L), class = c(&quot;tbl_df&quot;, 
  &quot;tbl&quot;, &quot;data.frame&quot;))
  
  df2&lt;-structure(list(ID = c(1, 2, 3, 1, 2, 3), weight = c(69, 58, 35, 
  65, 24, 15), date = c(3, 3, 3, 2, 2, 2)), row.names = c(NA, -6L
  ), class = c(&quot;tbl_df&quot;, &quot;tbl&quot;, &quot;data.frame&quot;))
  </code></pre>
  <p>The final outcome should be sth that looks like this:
  <a href="https://i.stack.imgur.com/tBGd4.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/tBGd4.png" alt="enter image description here" /></a></p>