 vehicles (in blue):</p>
<div class="sourceCode"><pre class="sourceCode r"><code class="sourceCode r"><span class="kw"><a href="../reference/cplot.html">cplot</a></span>(x1, <span class="dt">x =</span> <span class="st">"wt"</span>, <span class="dt">dx =</span> <span class="st">"drat"</span>, <span class="dt">what =</span> <span class="st">"effect"</span>, 
      <span class="dt">data =</span> mtcars[mtcars[[<span class="st">"am"</span>]] <span class="op">==</span><span class="st"> </span><span class="dv">0<