title: Group value in range r
body: <p>I have my table(input)</p>
  
  <pre><code>name   value
  Rob    35
  Helen  20
  Sergey 16
  Linn   40
  Elena  23
  Mary   40
  </code></pre>
  
  <p>And I want to count how many of my users is in custom range (0-20,21-30,>30)(output):</p>
  
  <pre><code>range  num
  0-20   2
  21-30  1
  30-    3 
  </code></pre>
  
  <p>THX! Sorry if this theme not new, but I can't find answer!</p>