current number of contextual features in <code>context$d</code>.</p>
<p>To transparently support <code>Bandits</code> generating either contextual feature vectors or matrices, <code>contextual</code>’s <code>Policies</code> generally use the <code><a href="../../reference/get_arm_context.html">get_arm_context(context, arm)</a></code> utility function to obtain the current <code>X</code> for a particular arm, or the <code><a href="../../reference/get_full_context.html">get_full_context(context)</a></code> 