-link">as.factor</a></span><span class="op">(</span><span class="fu"><a href="../reference/drop_undeclare.html">drop_na</a></span><span class="op">(</span><span class="va">x4</span><span class="op">)</span><span class="op">)</span></span>
<span><span class="co">#&gt; [1] Left   Middle Right  &lt;NA&gt;</span></span>
<span><span class="co">#&gt; Levels: Left Middle Right</span></span></code></pre></div>
<p>Converting the declared missing values to factor levels is something
for which the function <code class