title: 'Index' object has no attribute 'tz_localize'
body: <p>I'm trying to convert all instances of 'GMT' time in a time/date column ('Created_At') in a csv file so that it is all formatted in 'EST'.
  Please see below:</p>
  
  <pre><code>import pandas as pd
  from pandas.tseries.resample import TimeGrouper
  from pandas.tseries.offsets import DateOffset
  from pandas.tseries.index import DatetimeIndex
  
  cambridge = pd.read_csv('\Users\cgp\Desktop\Tweets.csv')
  cambridge['Created_At'] = pd.to_datetime(pd.Series(cambridge['Created_At']))
  cambridge.set_index('Created_At', drop=False, inplace=True)
  cambridge.index = cambridge.index.tz_localize('GMT').tz_convert('EST')
  cambridge.index = cambridge.index - DateOffset(hours = 12)
  </code></pre>
  
  <p>The error I'm getting is: </p>
  
  <pre><code>cambridge.index = cambridge.index.tz_localize('GMT').tz_convert('EST')
  </code></pre>
  
  <blockquote>
    <p>AttributeError: 'Index' object has no attribute 'tz_localize'</p>
  </blockquote>
  
  <p>I've tried various different things but am stumped as to why the Index object won't recognized the tz_attribute. Thank you so much for your help!</p>