Pandas groupby datatime index, possible bug
<p>I have a Pandas DataFrame with a column that is a tz-aware TimeStamp and I tried to groupby(level=0).first(). I get an incorrect result. Am I missing something or is it a pandas bug?</p>

<pre><code>x = pd.DataFrame(index = [1,1,2,2,2], data = pd.date_range("7:00", "9:00", freq="30min", tz = 'US/Eastern'))

In [58]: x
Out[58]: 


     0
1 2016-09-08 07:00:00-04:00
1 2016-09-08 07:30:00-04:00
2 2016-09-08 08:00:00-04:00
2 2016-09-08 08:30:00-04:00
2 2016-09-08 09:00:00-04:00

In [59]: x.groupby(level=0).first()
Out[59]: 
                          0
1 2016-09-08 11:00:00-04:00
2 2016-09-08 12:00:00-04:00
</code></pre>

<p>This is actually a pandas bug reported here:</p>

<p><a href="https://github.com/pydata/pandas/issues/10668" rel="nofollow">https://github.com/pydata/pandas/issues/10668</a></p>

python pandas timestamp