Numpy strings cannot be loaded

[moritzlayer]

Hi, I just came across the following issue:

If you have numpy strings as keys of a dictionary and you save this dictionary, the h5py_wrapper raises the error

ValueError: malformed node or string: 
    <ast.Name object at 0x7fcfa1870970>

when trying to load the file. This can be reproduced using the following test (using pytest):

import pytest
import numpy as np
import h5py_wrapper as h5

from unittest import TestCase


def test_saving_and_consecutive_loading_of_numpy_string_keys(tmpdir):
    file = 'test.h5'
    keys = ['a', 'b', 'c']
    
    # this makes the keys numpy strings
    keys = np.atleast_1d(keys)
    output = {key: i for i, key in enumerate(keys)}

    # create temporary directory to save test file into
    tmp_test = tmpdir.mkdir('tmp_test')
    with tmp_test.as_cwd():
        h5.save(file, output)
        input = h5.load(file)
        TestCase().assertDictEqual(output, input)

The problem seems to be line 296 in wrapper.py where key_type is compared to ['str', 'unicode', 'string_'], but a numpy string leads to key_type = 'str_'.