http://drotner.org/articles/2007/10/23/ruby-method-of-the-day-array-intersection en-us 40 by Kelly McCauley <h3>Signature</h3> <div class="CodeRay"> <div class="code"><pre>array &amp; other_array <span class="c">#=&gt; new_array</span> </pre></div> </div> <p><code>array &#38; other_array</code> returns <code>new_array</code> which contains the <a href="http://en.wikipedia.org/wiki/Set_intersection">intersections</a> of the two arrays. Only unique intersections will be returned. In other words, if <code>array</code> and/or <code>other_array</code> contain duplicate elements, <code>new_array</code> will not contain duplicate intersections.</p> <h3>Examples</h3> <table class="CodeRay"><tr> <td class="line_numbers" title="click to toggle" onclick="with (this.firstChild.style) { display = (display == '') ? 'none' : '' }"><pre>1<tt> </tt>2<tt> </tt>3<tt> </tt>4<tt> </tt>5<tt> </tt></pre></td> <td class="code"><pre ondblclick="with (this.style) { overflow = (overflow == 'auto' || overflow == '') ? 'visible' : 'auto' }">a = [<span class="i">1</span>,<span class="i">2</span>,<span class="i">3</span>,<span class="i">4</span>,<span class="i">5</span>,<span class="i">6</span>,<span class="i">7</span>,<span class="i">8</span>,<span class="i">8</span>,<span class="i">9</span>,<span class="i">10</span>] <span class="c">#=&gt; [1, 2, 3, 4, 5, 6, 7, 8, 8, 9, 10]</span><tt> </tt>a &amp; [<span class="i">0</span>,<span class="i">2</span>,<span class="i">4</span>,<span class="i">9</span>,<span class="i">11</span>] <span class="c">#=&gt; [2, 4, 9]</span><tt> </tt>a &amp; [<span class="i">0</span>,<span class="i">11</span>,<span class="i">22</span>] <span class="c">#=&gt; []</span><tt> </tt>a &amp; [<span class="i">0</span>,<span class="i">8</span>,<span class="i">8</span>,<span class="i">7</span>,<span class="i">6</span>,<span class="i">-3</span>] <span class="c">#=&gt; [6, 7, 8]</span><tt> </tt>a &amp; [<span class="i">0</span>,<span class="i">8</span>,<span class="i">8</span>,<span class="i">7</span>,<span class="i">6</span>,<span class="i">-3</span>] &amp; [<span class="i">1</span>,<span class="i">2</span>,<span class="i">3</span>,<span class="i">4</span>,<span class="i">5</span>,<span class="i">6</span>] <span class="c">#=&gt; [6]</span><tt> </tt></pre></td> </tr></table> <h3>Documentation Reference</h3> <p>Ruby version 1.8.6</p> <p><a href="http://www.ruby-doc.org">www.ruby-doc.org</a> : <a href="http://www.ruby-doc.org/core/classes/Array.html#M002235">Array.&#38;</a></p> Tue, 23 Oct 2007 00:01:00 -0500 urn:uuid:e1a90b95-b955-47be-a725-9bc52ed71c4d Kelly McCauley http://drotner.org/articles/2007/10/23/ruby-method-of-the-day-array-intersection Ruby Method of the Day Programming ruby rmotd