Round trip through HDF5 with format=table and localized DatetimeIndex discards index name

[jzwinck]

This should work, but the assert fails:

import pandas as pd

df = pd.DataFrame({'a': [1,2,3]})
df.index = pd.DatetimeIndex([1234567890123456787, 1234567890123456788, 1234567890123456789])
df.index = df.index.tz_localize('UTC') # this line makes the index name go away
df.index.name = 'expected'
df.to_hdf('hello.h5', 'world', format='table')

df2 = pd.read_hdf('hello.h5', 'world')
assert df2.index.name == df.index.name, "HDF5 stored name not expected: {}".format(df2.index.name)

It works fine if you don't localize the DatetimeIndex, or if you don't use format='table'.

The index name "expected" is actually stored in the "info" attribute inside the HDF5 file whether it's localized or not. But the format is slightly different. If not localized:

       (dp7
       Vindex_name
       p8
       Vexpected

If localized:

       (tRp10
       sVindex_name
       p11
       Vexpected

I don't know enough to say whether the bug is in read_hdf(), to_hdf(), or PyTables.

I'm using Pandas 0.18.1.

[jreback]

thought there was an issue about this, but can't seem to find it.

So the attribute is saved. Must not be set on the read-back somehow.

In [38]: store.root.world._v_attrs
Out[38]:
/world._v_attrs (AttributeSet), 15 attributes:
   [CLASS := 'GROUP',
    TITLE := '',
    VERSION := '1.0',
    data_columns := [],
    encoding := 'UTF-8',
    index_cols := [(0, 'index')],
    info := {1: {'type': 'Index', 'names': [None]}, 'index': {'tz': <UTC>, 'index_name': 'expected'}},
    levels := 1,
    metadata := [],
    nan_rep := 'nan',
    non_index_axes := [(1, ['a'])],
    pandas_type := 'frame_table',
    pandas_version := '0.15.2',
    table_type := 'appendable_frame',
    values_cols := ['values_block_0']]

[jreback]

@jzwinck HDFStore is a meta-data layer on top of PyTables. pull-requests are welcome.