Pandas dataframe to and from HDF file -> C-Contiguous?

[Jonas Baumann]

Hallo,

Recently after playing with pandas dataframe and HDF5 files, I discovered that after storing a dataframe and then reading it, the columns became non-contiguous. Like:

```

>>> df = pd.DataFrame({"a":[1,2,3], "b":[4,5,6]})

>>> df["a"].values.flags

  C_CONTIGUOUS : True

  F_CONTIGUOUS : True

>>> df.to_hdf("test.h5", "all")

>>> df1 = pd.read_hdf("test.h5", "all")

>>> df1["a"].values.flags

  C_CONTIGUOUS : False

  F_CONTIGUOUS : False

```

I am wondering if I missed some configure option or done anything wrong, any help would be appreciated. Thanks!