title: Finding non-numeric data in a data frame or vector
body: <p>I have read in some lengthy data with <code>read.csv()</code>, and to my surprise the data is coming out as factors rather than numbers, so I'm guessing there must be at least one non-numeric item in the data. How can I find where these items are?</p>
  <p>For example, if I have the following data frame:</p>
  <pre><code>df &lt;- data.frame(c(1,2,3,4,&quot;five&quot;,6,7,8,&quot;nine&quot;,10))
  </code></pre>
  <p>I would like to know that rows 5 and 9 have non-numeric data. How would I do that?</p>