Safe metadata and multiple datasets

h5.py

import numpy as np
import h5py

SIZE = 500000

with h5py.File("test.hdf", "w") as f:
    f["first"] = np.random.random(SIZE)
    f["first"].attrs["git id"] = "yay this is a string"
    f["second"] = np.random.random(SIZE)
    f["second"].attrs["git id"] = "yay this is a string"
    f["third"] = np.random.random(SIZE)
    f["third"].attrs["wo"] = [1, 2, 3, 4, 5]
    f["third"].attrs["bla"] = "terrow"

with h5py.File("testc.hdf", "w") as f:
    f.create_dataset('first', data=np.random.random(SIZE), compression='gzip', compression_opts=9)
    f["first"].attrs["git id"] = "yay this is a string"
    f.create_dataset('second', data=np.random.random(SIZE), compression='gzip', compression_opts=9)
    f["second"].attrs["git id"] = "yay this is a string"
    f.create_dataset('third', data=np.random.random(SIZE), compression='gzip', compression_opts=9)
    f["third"].attrs["wo"] = [1, 2, 3, 4, 5]
    f["third"].attrs["bla"] = "terrow"


for name in ("test.hdf", "testc.hdf"):
    with h5py.File("test.hdf", "r") as f:
        print("Keys: %s" % f.keys())
        for k in f.keys():
            print("Data: %s" % f[k])
            print("Attr: %s" % f[k].attrs.keys())
            for ak in f[k].attrs.keys():
                print("Attr val: %s" % f[k].attrs[ak])