title: How to remove a relative shift when plotting with pandas?
body: <p>I have this data that I am trying to plot using pandas:</p>
  
  <pre><code>df['SGP_sum'].iloc[0:16] = 
  Date
  2018-01-01 00:00:00     99.998765
  2018-01-01 01:00:00     99.993401
  2018-01-01 02:00:00    100.005571
  2018-01-01 03:00:00    100.027737
  2018-01-01 04:00:00    100.022474
  2018-01-01 05:00:00    100.039800
  2018-01-01 06:00:00    100.043310
  2018-01-01 07:00:00    100.045207
  2018-01-01 08:00:00    100.045201
  2018-01-01 09:00:00    100.043810
  2018-01-01 10:00:00    100.042977
  2018-01-01 11:00:00    100.054589
  2018-01-01 12:00:00    100.052009
  2018-01-01 13:00:00    100.040163
  2018-01-01 14:00:00    100.009129
  2018-01-01 15:00:00     99.975595
  Name: SGP_sum, dtype: float64
  </code></pre>
  
  <p>But when I plot it, this is what I see: ( I get negative values in the display)</p>
  
  <pre><code>df['SGP_sum'].iloc[0:16].plot()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/orUkA.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/orUkA.png" alt="enter image description here"></a></p>