how to combine multiple hdf5 files
In [1]: import h5py as h5
In [2]: hf1 = h5.File("f1.h5")
In [3]: hf2 = h5.File("f2.h5")
In [4]: hf1.create_dataset("val", data=35)
Out[4]: <HDF5 dataset "val": shape (), type "<i8">
In [5]: hf1.create_group("g1")
Out[5]: <HDF5 group "/g1" (0 members)>
In [6]: hf1.get("g1").create_dataset("val2", data="Thing")
Out[6]: <HDF5 dataset "val2": shape (), type "|O8">
In [7]: hf1.flush()
In [8]: h5.h5o.copy(hf1.id, "g1", hf2.id, "newg1")
In [9]: h5.h5o.copy(hf1.id, "val", hf2.id, "newval")
In [10]: hf2.values()
Out[10]: [<HDF5 group "/newg1" (1 members)>, <HDF5 dataset "newval": shape (), type "<i8">]
In [11]: hf2.get("newval").value
Out[11]: 35
In [12]: hf2.get("newg1").values()
Out[12]: [<HDF5 dataset "val2": shape (), type "|O8">]
In [13]: hf2.get("newg1").get("val2").value
Out[13]: 'Thing'