title: list.files: regex pattern not working on windows?
body: <p>I can access and get the path of my file with <code>file.choose()</code>:</p>
  <pre><code>&quot;D:\\amca\\reportes_mov\\data_mym\\mym_total_csv\\hhhh-2020-11-09.csv&quot;
  </code></pre>
  <p>I'm using a project, so I don't have to type the whole path, but after <code>reportes_mov</code>. Why my list files is empty after I run it?</p>
  <pre><code>files  &lt;- list.files(pattern = 'data_mym\\/mym_total_csv\\/hhhh-2020-[0-9]{2}-[0-9]{2}\\.csv')
  </code></pre>
  <p>Other attemp: still empty.</p>
  <pre><code>files  &lt;- list.files(pattern = 'data_mym\\mym_total_csv\\hhhh-2020-[0-9]{2}-[0-9]{2}\\.csv')
  </code></pre>