
</pre></div>
</div></div>
    <p>
    The R package 'vwline' provides several functions
    that draw curves based on X-splines, but with the width of the
    X-spline allowed to vary along the length of the curve.
    The following R code shows an example, where the width of the
    X-spline increases smoothly along the length of the line.
  </p>
<div class="chunk" id="unnamed-chunk-4"><div class="rcode"><div class="source"><pre class="knitr r"><span class="hl kwd">library</span><span class="hl std">(vwli