title: How to find the minimum and maximum in many rows per single value
body: <p>I have the following dataset:</p>
  
  <pre><code>Class     
  A       5     9     2     6
  A       13    8     
  A       4     8     3     10    6
  B       12    5     11     
  B       7     1     17    6     8     1
  </code></pre>
  
  <p>What I want is to find the maximum and minimum value for each class in all the rows that are related to that class. In this case, I should get:</p>
  
  <pre><code>Class    Max    Min
  A        13     2
  B        33     1
  </code></pre>
  
  <p>Note that the values don't have headers.</p>
  
  <p>How can I do that?</p>