t">labels=</span><span class="kw">c</span>(<span class="st">"front"</span>, <span class="st">"back"</span>)))

## polar plot with two variables
m &lt;-<span class="st"> </span><span class="kw">melt</span>(combined, <span class="dt">id=</span><span class="kw">c</span>(<span class="st">"angle"</span>, <span class="st">"side"</span>))

<span class="co"># custom labels for polar plot</span>
mylabels &lt;-<span class="st"> </span><span class="kw">c</span>(-<span class="dv">90</span>,-<span class="dv">45</span>,<