title: Ruby array map and join in one loop
body: <p><strong>Array exemple</strong></p>
  
  <pre><code>[
   [
     "Francis",
     "Chartrand",
     "email@email.com"
   ],
   [
     "Francis",
     "Chartrand",
     "second_email@email.com"
   ],...
  ]
  </code></pre>
  
  <p><strong>Result wanted</strong></p>
  
  <pre><code>"email@email.com, second_email@email.com, ..."
  </code></pre>
  
  <p><strong>My solution (two loop)</strong></p>
  
  <pre><code>array.map{|a| a[2]}.join(", ")
  </code></pre>
  
  <p>Is it possible to do this with one loop?</p>