rdocumentation.org/packages/base/topics/data.frame">data.frame</a></span>(<span class="dt">id =</span> <span class="dv">1</span><span class="op">:</span><span class="dv">4</span>, </a>
<a class="sourceLine" id="cb1-2" data-line-number="2">                <span class="dt">chromosome =</span> <span class="kw"><a href="https://www.rdocumentation.org/packages/base/topics/c">c</a></span>(<span class="st">"chr1"</span>, <span class="st">"chr1"</span>, <span class="st">"chr2"</span>, <span class="st">"chr2"</span>