title: Vertically split one column in Pandas
body: <p>I would like to split column <code>hobbies</code> by comma from the following dataframe, then vertically set them respectively:</p>
  
  <pre><code>   id   name       hobbies
  0   1   John  TV, computer
  1   2  Steve  travel, film
  2   3    Jim     swim, jog
  </code></pre>
  
  <p>How could I get an output like this? Thank you.</p>
  
  <pre><code>   id   name   hobbies
  0   1   John        TV
  1   1   John  computer
  2   2  Steve    travel
  3   2  Steve      film
  4   3    Jim      swim
  5   3    Jim       jog
  </code></pre>