title: Group by, array of arrays in ruby
body: <p>I have an array as follows</p>
  
  <pre><code>    some_array = [["FANUC CORP", "100048", 9],
                    ["FANUC CORP", "100048", 26],
                    ["FANUC CORP", "100048", 23],
                    ["FANUC CORP", "100048", 111]]
  </code></pre>
  
  <p>And I want to group by in the following way:</p>
  
  <p><code>=&gt; ["FANUC CORP", "100048", [9, 26,23,111]]</code></p>
  
  <p>Can anyone suggest something, any help will be appreciated</p>