title: Add rows to dataframes from list of dataframes until number of rows is 1000 for every data frame in list
body: <p>I have a list with dataframes, each of them has a different number of rows. Now I'd like to add rows to every dataframe of the list, until every dataframe of the list has 1000 rows. The added rows should all only contain NAs. All dataframes of the list contain of three columns.</p>
  
  <p>I first defined the function</p>
  
  <pre><code>adder &lt;- function(x) {rbind(x, c(NA, NA, NA))}
  </code></pre>
  
  <p>and then applied it to every dataframe of the list using lapply</p>
  
  <pre><code>dflisttest &lt;- lapply(dflisttest, adder)
  </code></pre>
  
  <p>However, this would add one row to every dataframe rather than only to the ones that have less than 1000 rows. How could I loop it so that all dataframes of the list automatically fill up to 1000 rows?</p>