title: get min and max from a specific column scala spark dataframe
body: <p>I would like to access to the min and max of a specific column from my dataframe but I don't have the header of the column, just its number, so I should I do using scala ?</p>
  
  <p>maybe something like this : </p>
  
  <pre><code>val q = nextInt(ncol) //we pick a random value for a column number
  col = df(q)
  val minimum = col.min()
  </code></pre>
  
  <p>Sorry if this sounds like a silly question but I couldn't find any info on SO about this question :/</p>