title: Pandas - value_counts on multiple values in one cell
body: <p>I have a dataframe which has a column with multiple values, separated by a comma like this:</p>
  
  <pre><code>Country
  Australia, Cuba, Argentina
  Australia
  United States, Canada, United Kingdom, Argentina
  </code></pre>
  
  <p>I would like to count each unique value, similar to value_counts, like this:</p>
  
  <pre><code>Australia: 2
  Cuba: 1
  Argentina: 2
  United States: 1
  </code></pre>
  
  <p>My simplest method is shown below, but I suspect that this can be done more efficiently and neatly. </p>
  
  <pre><code>from collections import Counter
  Counter(pd.DataFrame(data['Country'].str.split(',', expand=True)).values.ravel())
  </code></pre>
  
  <p>Cheers</p>