title: unique values with count of each value for each column in Pandas dataframe
body: <p>How can I get unique values with count of each value for each column in a pandas dataframe using for loop:</p>
  
  <p>Following code gives me count of each unique value for each column but I want the values as well.</p>
  
  <pre><code>import pprint
  
  col_uni_val={}
  for i in data.columns:
      col_uni_val[i] = len(data[i].unique())
  
  pprint.pprint(col_uni_val)
  </code></pre>
  
  <p>For example:</p>
  
  <pre><code>A  B
  1  4
  1  4
  2  6
  2  6
  2  6
  3  6
  </code></pre>
  
  <p>I want my output as :</p>
  
  <pre><code>A:
  1 - 2
  2 - 3
  3 - 1
  
  B:
  4 - 2
  6 - 4
  </code></pre>
  
  <p>Also since my number of columns is huge can i do this using indexed loop.</p>