title: How add plot to subplot matplotlib
body: <p>I have plots like this </p>
  
  <pre><code>fig = plt.figure()
  desire_salary = (df[(df['inc'] &lt;= int(salary_people))])
  print desire_salary
  # Create the pivot_table
  result = desire_salary.pivot_table('city', 'cult', aggfunc='count')
  
  # plot it in a separate step. this returns the matplotlib axes
  ax = result.plot(kind='bar', alpha=0.75, rot=0, label="Presence / Absence of cultural centre")
  
  ax.set_xlabel("Cultural centre")
  ax.set_ylabel("Frequency")
  ax.set_title('The relationship between the wage level and the presence of the cultural center')
  plt.show()
  </code></pre>
  
  <p>I want to add this to <code>subplot</code>. I try </p>
  
  <pre><code>fig, ax = plt.subplots(2, 3)
  ...
  ax = result.add_subplot()
  </code></pre>
  
  <p>but it returns 
  AttributeError: 'Series' object has no attribute 'add_subplot'`. How can I check this error?</p>