CODEWITHSUNDEEP
pythonarraysaudio
user2858910
user2858910

Reputation: 129

Loading audio waveform files in python. ValueError: too many values to unpack

from scipy.io.wavfile import read

filepath = glob.glob('*.wav') #list

rate,data = [read(fp) for fp in filepath]

and I get :

ValueError: too many values to unpack

but i can load only once a time.

like this:

rate,data = read('001.wav')
print rate
print data

and I get:

44100
[0 0 0 ..., 0 0 0]

How could I load the rate and data to two arrays, and if I do :

datas = [read(fp) for fp in filepath]

I will get :

[(44100, array([0, 0, 0, ..., 0, 0, 0], dtype=int16)), (44100, array([0, 0, 0, ..., 0, 0, 1], dtype=int16)), ..., (44100, array([0, 0, 0, ..., 0, 0, 0], dtype=int16))]

or there is any way I can split the datas to rate and data after loading.

Thanks.

Upvotes: 1

Views: 602

Answers (2)

metakermit
metakermit

Reputation: 22341

You can split it after loading using the inverse zip function (as explained in this answer):

In [13]: rate, data = zip(*datas)

In [14]: rate
Out[14]: (44100, 44100)

In [15]: data
Out[15]: (array([0, 0, 0, 0, 0, 0]), array([0, 0, 0, 0, 1]))

I would say that this is an acceptable way to do it in this scenario, although I think using a more classical for loop, where you append to lists, without using list comprehension, would be cleaner:

rates = []
datas = []
for fp in filepath:
    rate, data = read(fp)
    rates.append(rate)
    datas.append(data)

The reason you got a ValueError in the first case is because you are unpacking a list of all tuples for each of your files (obviously more than 2 given the error message) into only two variables - rate and data.

Upvotes: 1

wflynny
wflynny

Reputation: 18541

You can use zip(*x) to format them into one list of rates and one list of the data lists.

raw_data = [read(fp) for fp in filepath]
rates, data = zip(*raw_data)

For example,

raw_data = zip(range(10), range(20, 30))
# [(0, 20), (1, 21), (2, 22), (3, 23), (4, 24), (5, 25), (6, 26), (7, 27), (8, 28), (9, 29)]

zip(*raw_data)
# [(0, 1, 2, 3, 4, 5, 6, 7, 8, 9), (20, 21, 22, 23, 24, 25, 26, 27, 28, 29)]

Upvotes: 1

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