title: bind columns with different number of rows
body: <p>I want to create iteration that takes a list (which is column of another dataframe) and add it to the current data frame as column. but the length of the columns are not equal. So, I want to generate NA as unmatched rows.</p>
  
  <pre><code>seq_actions=as.data.frame(x = NA)
  for(i in 1:20){
    temp_seq=another_df$c1[some conditions]  
    seq_actions=cbind(temp_seq,seq_actions)
  }
  </code></pre>
  
  <p>to simplify, lets say i have </p>
  
  <pre><code>df
  1  3
  3  4
  2  2
  </code></pre>
  
  <p>adding the list of 5,6 as new column to df, so I want:</p>
  
  <pre><code> df
      1  3  5
      3  4  6
      2  2  NA
  </code></pre>
  
  <p>another adding list is 7 7 7 8, so my df will be:</p>
  
  <pre><code>df
     1  3  5  7
     3  4  6  7
     2  2  NA 7
     NA NA NA 8
  </code></pre>
  
  <p>How can I do it?</p>