span class="va">trapnell.path</span> <span class="op">&lt;-</span> <span class="st">"myoblast-differentiation_trapnell.rds"</span>
<span class="kw">if</span> <span class="op">(</span><span class="op">!</span><span class="fu"><a href="https://rdrr.io/r/base/files.html" class="external-link">file.exists</a></span><span class="op">(</span><span class="va">trapnell.path</span><span class="op">)</span><span class="op">)</span> <span class="op">{</span>
  <span class="fu"><a href="https://rdrr.io/r/utils/download