title: Cannot remove "," in data.frame(they said "Unexpected numeric constant.")
body: <p>I have that df.</p>
  <p><a href="https://i.stack.imgur.com/QzYo3.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QzYo3.png" alt="enter image description here" /></a></p>
  <p>I'd like to remove comma in field in cloumn &quot;2019&quot; ~ &quot;2015&quot;.</p>
  <p>So I used the following function.</p>
  <pre><code>(df &lt;- as.numeric(gsub(&quot;,&quot;, &quot;&quot;, df$2019)))
  </code></pre>
  <p>but The R said</p>
  <blockquote>
  <p>&quot;Error : that is unexpected numeric constant.
  df &lt;- as.numeric(gsub(&quot;,&quot;, &quot;&quot;, df$2019)
  ^       &quot;</p>
  </blockquote>
  <p>How can I solve the problem??</p>