title: Transpose 2 associative arrays of unequal size to form an associative 2d array
body: <p>Example:</p>
  <pre><code>$arr1 = array('a' =&gt; &quot;1&quot;, 'b' =&gt; &quot;2&quot;, 'c' =&gt; &quot;3&quot;, 'z' =&gt; &quot;4&quot;);
  $arr2 = array('a' =&gt; &quot;9&quot;, 'b' =&gt; &quot;8&quot;, 'c' =&gt; &quot;7&quot;, 'd' =&gt; &quot;6&quot;, 'e' =&gt; &quot;5&quot;);
  </code></pre>
  <p>Output:</p>
  <pre><code>$result = array(
      'a' =&gt; array( 'f1' =&gt; &quot;1&quot;, 'f2' =&gt; &quot;9&quot;),
      'b' =&gt; array( 'f1' =&gt; &quot;2&quot;, 'f2' =&gt; &quot;8&quot;),
      'c' =&gt; array( 'f1' =&gt; &quot;3&quot;, 'f2' =&gt; &quot;7&quot;),
      'd' =&gt; array( 'f1' =&gt; &quot;0&quot;, 'f2' =&gt; &quot;6&quot;),
      'e' =&gt; array( 'f1' =&gt; &quot;0&quot;, 'f2' =&gt; &quot;5&quot;),
      'z' =&gt; array( 'f1' =&gt; &quot;4&quot;, 'f2' =&gt; &quot;0&quot;),
  );
  </code></pre>
  <p>The size of $arr1 can be '&gt;', '&lt;' or '=' size of $arr2</p>