title: Python Pandas Where on Date Index
body: <p>I'm trying to split my dataframe based on a date, which is the index.  My data looks like this:</p>
  
  <pre><code>  print(df.head())
  
    date_time             value   anomaly                         
    2014-11-23 00:00:00   0.414183    0   
    2014-11-23 01:00:00   0.526574    0
    2014-11-23 02:00:00   0.734324    1
  </code></pre>
  
  <p>My code this far:</p>
  
  <pre><code> df_split = df.where(df.index &gt;= '2014-11-23 01:00:00')
  </code></pre>
  
  <p>My desired output would be:</p>
  
  <pre><code>  2014-11-23 01:00:00   0.526574    0
    2014-11-23 02:00:00   0.734324    1
  </code></pre>
  
  <p>My error I get is: </p>
  
  <pre><code>  ValueError: Array conditional must be same shape as self
  </code></pre>