Filter out keys from multidim array
<p>I have the following array:</p>

<pre><code>array(2) {
  [0] =&gt; array(4) {
    ["presentation_id"] =&gt; int(143)
    ["user_id"] =&gt; int(2)
    ["session_id"] =&gt; int(46)
    ["submission_id"] =&gt; int(190)
}
[1] =&gt; array(4) {
    ["presentation_id"] =&gt; int(144)
    ["user_id"] =&gt; int(2)
    ["session_id"] =&gt; int(46)
    ["submission_id"] =&gt; int(190)
}
</code></pre>

<p>What I want is to have an array consisting of just certain keys of this array, for example:</p>

<pre><code>array(2) {
  [0] =&gt; array(4) {
    ["presentation_id"] =&gt; int(143)
    ["user_id"] =&gt; int(2)
}
[1] =&gt; array(4) {
    ["presentation_id"] =&gt; int(144)
    ["user_id"] =&gt; int(2)
}
</code></pre>

<p>Any ideas?</p>
