Python numpy append ascii data type

Question

I'm working on a tensorflow project that learns from mp3 files. I have opened the binary data and read it. Then I have converted the binary to ascii. Then I have confirmed that the conversion. But then when I go to append it to a numpy array, it appends blank data.

    dataset = np.ndarray(shape=(len(image_files)),
                     dtype=np.dtype('a16'))
    f = open(image_file, 'rb')
    temp = f.read()
    # sound = AudioSegment.from_mp3(image_file)
    # raw_data = sound._data
    audio_array = binascii.b2a_base64(temp)
    # print(audio_array)
    np.append(dataset, audio_array)
    print(dataset)
    print(COUNT)

when I print(audio_array) I get the following

czDne2AxSfpq0DMK9MjrzBw2/F6sMWm/XD47FTN0aXUkq/kIKP2mK3satPUWf9/zTV/t/dTf1Lf//uSBOmNA3pZU6sPOvJ0q0p2PUn2SfFjVAesq8FQrCuo9BUh1f9zRCt//yh7OOuhMogrixdsGrTHd+tGSSaAkPrfqnQ48vFMd6fSBOErLeOipQXe7zkuSt7aFR5J7v3MA3b+gMYpO32b0Kxo/ee/WcN/727XSS/p/1H/8hf5cBCEwWAHBfxdhEKHVomiae73PzIai5...

But then when I go to print dataset I get the following:

['' '' '' ..., '' '' '']
2

unutbu · Accepted Answer · 2016-04-02 18:13:50Z

1

np.append(dataset, audio_array) returns a new array; it does not modify dataset. So change

np.append(dataset, audio_array)

to

dataset = np.append(dataset, audio_array)

answered Apr 2, 2016 at 18:13

unutbu

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Sawel · Accepted Answer · 2016-04-02 18:25:06Z

0

Try and use the help function of python, it is really helpful. In this case notice:

help(numpy.append)

Outputs: ....

    Returns
    -------
    append : ndarray
        A copy of `arr` with `values` appended to `axis`.  Note that
        `append` does not occur in-place: a new array is allocated and
        filled.  If `axis` is None, `out` is a flattened array.

Which means that the passed array isn't modified but copied instead, you must store the return value in dataset:

dataset = numpy.append(dataset, audio_array)

answered Apr 2, 2016 at 18:25

Sawel

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