title: converting dataframe with label to array in julia
body: <p>I have data frame with header in Julia , but I need to convert this to array for some filtering , there is some similar post that people suggest
  using :</p>
  
  <pre><code>iris[:, 1:3]
  </code></pre>
  
  <p>to get array from dataframe but this method wont work on dataframe with header , any suggestion what should I do ?</p>
  
  <p>dataframe format :</p>
  
  <pre><code>FP | C1 | Cz | C2 ....
  *  | *  | *  | *  ....
  .  | .  | .  | .  ....
  .  | .  | .  | .  ....
  .  | .  | .  | .  ....
  </code></pre>