Already tz-aware when reading hdf5 generated by Python2 in Python3
This is a follow up with Issue 14307 that was closed. There was a request for a reproducible example, but since the author who reported the issue first did not respond, the Issue was closed.

I am currently experiencing the same issue. And I posted a reproducible example on StackOverflow here:

[StackOverflow ](https://stackoverflow.com/questions/39640860/already-tz-aware-error-when-reading-h5-file-using-pandas-python-3-but-not-2)

Here is its Copy-paste:
I'm using Anaconda Python: 3.4.5 and 2.7.3. Both are using pandas 0.18.1.

Here is a reproducible example:

generate.py (to be executed with Python2):

`import pandas as pd
from pandas import HDFStore

index = pd.DatetimeIndex(['2017-06-20 06:00:06.984630-05:00', '2017-06-20 06:03:01.042616-05:00'], dtype='datetime64[ns, CST6CDT]', freq=None)

p1 = [0, 1]
p2 = [0, 2]

df1 = pd.DataFrame({"p1":p1, "p2":p2}, index=index)
df2 = pd.DataFrame({"p1":p1, "p2":p2, "i":index})

store = HDFStore("./test_issue.h5")
store['df'] = df1
store.close()
`

read_issue.py:
`import pandas as pd
from pandas import HDFStore

store = HDFStore("./test_issue.h5", mode="r")
df = store['/df']

store.close()
print(df)
`
Running read_issue.py in Python2 has no issues
But running it in Python3 produces Error with this traceback:

> Traceback (most recent call last): File "read_issue.py", line 5, in df = store['df'] File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/io/pytables.py", line 417, in getitem return self.get(key) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/io/pytables.py", line 634, in get return self._read_group(group) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/io/pytables.py", line 1272, in _read_group return s.read(**kwargs) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/io/pytables.py", line 2779, in read ax = self.read_index('axis%d' % i) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/io/pytables.py", line 2367, in read_index _, index = self.read_index_node(getattr(self.group, key)) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/io/pytables.py", line 2492, in read_index_node _unconvert_index(data, kind, encoding=self.encoding), **kwargs) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/indexes/base.py", line 153, in new result = DatetimeIndex(data, copy=copy, name=name, **kwargs) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/util/decorators.py", line 91, in wrapper return func(*args, **kwargs) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/tseries/index.py", line 321, in new raise TypeError("Already tz-aware, use tz_convert " TypeError: Already tz-aware, use tz_convert to convert. Closing remaining open files:./test_issue.h5...done

So, there is an issue with indices. However, if you save df2 in generate.py (datetime as a column, not as an index), then Python3 in read_issue.py produces a different error:

> Traceback (most recent call last): File "read_issue.py", line 5, in df = store['/df'] File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/io/pytables.py", line 417, in getitem return self.get(key) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/io/pytables.py", line 634, in get return self._read_group(group) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/io/pytables.py", line 1272, in _read_group return s.read(**kwargs) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/io/pytables.py", line 2788, in read placement=items.get_indexer(blk_items)) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/core/internals.py", line 2518, in make_block return klass(values, ndim=ndim, fastpath=fastpath, placement=placement) File "/home/denper/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/core/internals.py", line 90, in init len(self.mgr_locs))) ValueError: Wrong number of items passed 2, placement implies 1 Closing remaining open files:./test_issue.h5...done

Also, if you execute generate_issue.py in Python3 (saving either df1 or df2), then there is no problem executing read_issue.py in either Python3 or Python2

