title: combine multiple text files into one text file?
body: <p>I'm trying to combine multiple files into one, where each of them contains one column and I need to get one file with two columns and plot the resulted file like (x,y) as follows:</p>
  
  <pre><code>x       y       result
  1       4       1   4
  2       5       2   5
  3       6       3   6
  </code></pre>
  
  <p>and run the code for <code>n</code> text files.</p>
  
  <p>How can I do this?</p>