H5py store list of list of strings

Question

Is there a possibility in h5py to create a dataset which consists of lists of strings. I tried to create a nested datatype of variable length, but this results in segmentation fault in my python interpreter.

def create_dataset(h5py_file):
    data = [['I', 'am', 'a', 'sentecne'], ['another', 'sentence']]
    string_dt = h5py.special_dtype(vlen=str)
    nested_dt = h5py.special_dtype(vlen=string_dt)
    h5py_file.create_dataset("sentences", data=data, dtype = nested_dt)

Answer 1

If you don't intend to edit the hdf5 file (and potentially use longer strings), you can also simply use:

h5py_file.create_dataset("sentences", data=np.array(data, dtype='S'))

Answer 2

You should be able to get the functionality you want if you define your data as a numpy array of dtype=object as suggested in this post, rather than a list of lists.

def create_dataset(h5py_file):
    data = np.array([['I', 'am', 'a', 'sentence'], ['another', 'sentence']], dtype=object)
    string_dt = h5py.special_dtype(vlen=str)
    h5py_file.create_dataset("sentences", data=data, dtype=string_dt)