title: Pandas Histogram - y axis in time
body: <p>I have a DataFrame that is indexed with DateTime and on the histogram it shows up with counts.  Each count is 20 secs.<br>
  How can I change the y axis to display mins, hours, or days, instead of counts?</p>
  
  <p>Here's the top five rows of my DataFrame:</p>
  
  <pre><code>from pandas.lib import Timestamp
  df = pd.DataFrame({'A': {Timestamp('2013-01-20 00:00:16.726000'): 0.14746094,
                           Timestamp('2013-01-20 00:00:36.726002'): 0.13964844,
                           Timestamp('2013-01-20 00:00:56.726004'): 0.13574219,
                           Timestamp('2013-01-20 00:01:16.725997'): 0.14355469,
                           Timestamp('2013-01-20 00:01:36.725999'): 0.14746094},
                     'B': {Timestamp('2013-01-20 00:00:16.726000'): 3.5716574,
                           Timestamp('2013-01-20 00:00:36.726002'): 3.5716574,
                           Timestamp('2013-01-20 00:00:56.726004'): 3.5716574,
                           Timestamp('2013-01-20 00:01:16.725997'): 3.5716574,
                           Timestamp('2013-01-20 00:01:36.725999'): 3.5716574}})
  df.plot()
  </code></pre>
  
  <p>matplotlib v1.2.0
  pandas 0.10.1</p>
  
  <p><img src="https://i.stack.imgur.com/LIAmx.jpg" alt="Histogram"></p>
  
  <p>bump</p>