title: words frequency using pandas and matplotlib
body: <p>How can I plot word frequency histogram (for author column)using pandas and matplotlib from a csv file? My csv is like: id, author, title, language
  Sometimes I have more than one authors in author column separated by space </p>
  
  <pre><code>file = 'c:/books.csv'
  sheet = open(file)
  df = read_csv(sheet)
  print df['author']
  </code></pre>