title: Compare multiple year data on a single plot python
body: <p>I have two time series from different years stored in pandas dataframes. For example:</p>
  
  <pre><code>data15 = pd.DataFrame(
      [1,2,3,4,5,6,7,8,9,10,11,12],
      index=pd.date_range(start='2015-01',end='2016-01',freq='M'),
      columns=['2015']
  )
  data16 = pd.DataFrame(
      [5,4,3,2,1],
      index=pd.date_range(start='2016-01',end='2016-06',freq='M'),
      columns=['2016']
  )
  </code></pre>
  
  <p>I'm actually working with daily data but if this question is answered sufficiently I can figure out the rest. </p>
  
  <p>What I'm trying to do is overlay the plots of these different data sets onto a single plot from January through December to compare the differences between the years. I can do this by creating a "false" index for one of the datasets so they have a common year:</p>
  
  <pre><code>data16.index = data15.index[:len(data16)]
  ax = data15.plot()
  data16.plot(ax=ax)
  </code></pre>
  
  <p>But I would like to avoid messing with the index if possible. Another problem with this method is that the year (2015) will appear in the x axis tick label which I don't want. Does anyone know of a better way to do this? </p>