title: How to calculate count and percentage in groupby in Python
body: <p>I have following output after grouping by</p>
  
  <pre><code>Publisher.groupby('Category')['Title'].count()
  Category
  Coding          5
  Hacking         7
  Java            1
  JavaScript      5
  LEGO           43
  Linux           7
  Networking      5
  Others        123
  Python          8
  R               2
  Ruby            4
  Scripting       4 
  Statistics      2
  Web             3
  </code></pre>
  
  <p>In the above output I want the percentage also i.e for the first row <code>5*100/219</code> and so on. I am doing following</p>
  
  <pre><code> Publisher.groupby('Category')['Title'].agg({'Count':'count','Percentage':lambda x:x/x.sum()})
  </code></pre>
  
  <p>But it gives me an error. Please help</p>