title: Non consecutive combinations of array elements in R
body: <p>I want to generate all the possible combinations of nonadjacent elements in an array.</p>
  <p>For example:</p>
  <pre><code>array_a &lt;- c(&quot;A&quot;,&quot;B&quot;,&quot;C&quot;)
  </code></pre>
  <p>possible combinations would be : <code>AC</code> and <code>CA</code></p>
  <p>How can I implement this in R?</p>