s</h2>
        <ul class="book-toc list-unstyled">
<li><a class="" href="index.html">Welcome</a></li>
<li><a class="" href="foreword-by-professor-jeff-polzer.html">Foreword by Professor Jeff Polzer</a></li>
<li><a class="active" href="introduction.html">Introduction</a></li>
<li><a class="" href="the-basics-of-the-r-programming-language.html">The Basics of the R Programming Language</a></li>
<li><a class="" href="everywhere.html"><span class="header-section-number">1</span> Graphs Everywhere!</a></li>
<li><