title: How can I set the x-axis as datetimes on a bokeh plot?
body: <p>I'm using bokeh with an ipython notebook.</p>
  
  <p>I want to plot a line graph in bokeh using a pandas DataFrame containing datetimes:</p>
  
  <pre><code>import pandas as pd
  from datetime import datetime as dt
  from bokeh.io import output_notebook
  from bokeh.charts import Bar, Line, show
  
  df = pd.DataFrame(data=[1,2,3],
                    index=[dt(2015, 1, 1), dt(2015, 1, 2), dt(2015, 1, 3)],
                    columns=['foo'])
  
  output_notebook()
  show(Line(df))
  </code></pre>
  
  <p>However, bokeh uses microseconds! Why is this? How do I fix it?</p>
  
  <p><a href="https://i.stack.imgur.com/NDYJx.png"><img src="https://i.stack.imgur.com/NDYJx.png" alt="bokeh plot of line"></a></p>