title: Is it possible to call external R script from R markdown (.Rmd) in RStudio?
body: <p>It's fairly trivial to load external R scripts as per <a href="http://yihui.name/knitr/demo/externalization/" rel="nofollow noreferrer">this R Sweave example</a>:</p>
  
  <pre><code>&lt;&lt;external-code, cache=FALSE&gt;&gt;=
  read_chunk('foo-bar.R')
  @
  </code></pre>
  
  <p>Can the same be done for R Markdown?</p>