c plot
<span class="kw">qplot</span>(angle, perpendicular, <span class="dt">colour=</span>side, <span class="dt">data=</span>combined, <span class="dt">geom=</span><span class="st">"line"</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="kw">ggplot</span>(m, <span class="kw">aes</span>(angle, value)) +
<span class=