title: Merging data in a CSV file
body: <p>I have a CSV file formatted like this:</p>
  
  <pre><code>id @ word @ information @ other information
  </code></pre>
  
  <p>Sometimes, the first column has repeat occurrences:</p>
  
  <pre><code>001 @ cat @ makes a great pet @ mice
  002 @ rat @ makes a great friend @ cheese
  003 @ dog @ can guard the house @ chicken
  004 @ cat @ can jump very high @ fish
  </code></pre>
  
  <p>You can see, the first and last lines have duplicate data in column 2. I want to delete these duplicates (if column 2 is exactly the same) and merge the information contained in column three as well as the information contained in column four. The result is like this:</p>
  
  <pre><code>001 @ cat @ ① makes a great pet ② can jump very high @ ① mice ② fish
  002 @ rat @ makes a great friend @ cheese
  003 @ dog @ can guard the house @ chicken
  </code></pre>
  
  <ul>
  <li>I am using these symbols to number the data: "①", "②", "③", etc., but "(1)", "(2)", "(3)", etc. will be okay too.</li>
  </ul>
  
  <p>How can I merge the data in the cells in so that all of the data from the third column is assembled together into one cell and the data in the fourth column is assembled together into one cell?</p>