No conversion path for dtype ('<U1') issue

Question

I have a 2d list (Data_set) that contain a 3d array and a label(0 or 1), I want to make the h5py file with two datasets one for 3d array and the other for the label, this is my code for doing that: `

    data = []
    label = []
    for i in range(len(Data_set)):
        data.append(Data_set[i][0])# 3d array
        label.append(Data_set[i][1])#label
    data = np.array(data)
    label = np.array(label)
    dt = np.dtype('int16')
    with h5py.File(output_path+'dataset.h5', 'w') as hf:
        hf.create_dataset('data',dtype=dt ,data=data, compression='lzf')
        hf.create_dataset('label', dtype=dt, data=label, compression='lzf')

` the content of the 2d list is shown in the image below: but when I run the code it gives me an error: see the image below please help me to solve the problem?

Answer 1

Your labels are not integers, they are strings, that's a problem for HDF5. Your error message relates to an array consisting of strings of length 1. See Strings in HDF5 for more details.

You can convert to integers before or after you construct your NumPy array, here are a couple of examples:

label = np.array(label).astype(int)
# or, label = np.array(list(map(int, label)))

Alternatively, since your values are 0 or 1, choosing bool may be more efficient:

label = np.array(label).astype(int).astype(bool)

Also, consider holding meta-data as attributes.