title: Can't draw Histogram, 'x' must be numeric
body: <p>I have a data file with this format:</p>
  
  <pre><code>Weight    Industry Type  
  251,787   Kellogg  h  
  253,9601  Kellogg  a  
  256,0758  Kellogg  h  
  ....
  </code></pre>
  
  <p>I read the data and try to draw an histogram with this commands:</p>
  
  <pre><code> ce &lt;- read.table("file.txt", header = TRUE)
  
   we = ce[,1]
   in = ce[,2]
   ty = ce[,3]
  
  hist(we)
  </code></pre>
  
  <p>But I get this error:</p>
  
  <blockquote>
    <p>Error en hist.default(we) : 'x' must be numeric.</p>
  </blockquote>
  
  <p>What do I need to do in order to draw histograms for my three variables ?</p>