title: regex expression to match decimal numbers with comma as a separator
body: <p>As in title I need a regex expression in R that will match decimal numbers with comma as a separator in order to extract them from string with <code>stringr::str_extract</code> . Regex should catch the following cases:</p>
  
  <pre><code>0,1
  10
  1000,29
  3,23313
  </code></pre>
  
  <p>I have tried something like this <code>[0-9]+,[0-9]+</code> but it didn't work</p>