3

i tried to generate a spectrogram for each axis in my dataset here what i tried

dataset = np.loadtxt("trainingdataset.txt", delimiter=",", dtype = np.int32)

fake_size = 1415684
time = np.arange(fake_size)/1415684 # 1kHz
base_freq = 2 * np.pi * 100

x = dataset[:,2]
y = dataset[:,3]
z = dataset[:,4]

xyz_magnitude = x**2 + y**2 + z**2

to_plot = [('x', x), ('y', y), ('z', z), ('xyz', xyz_magnitude)]

for chl, data in to_plot:
    plt.figure(); plt.title(chl)
    d = plt.specgram(data, Fs=1000)
    plt.xlabel('Time [s]'); plt.ylabel('Frequency [Hz]')
    plt.show()

but it gives the following warning 

Warning (from warnings module):
  File "C:\Users\hadeer.elziaat\AppData\Local\Programs\Python\Python36\lib\site-packages\matplotlib\axes\_axes.py", line 7221
    Z = 10. * np.log10(spec)
RuntimeWarning: divide by zero encountered in log10

the dataset headers (patient number, time/millisecond, x-axis, y-axis, z-axis, label)

1,15,70,39,-970,0
1,31,70,39,-970,0
1,46,60,49,-960,0
1,62,60,49,-960,0
1,78,50,39,-960,0
1,93,50,39,-960,0
1,109,60,39,-990,0
Hadeer El-Zayat
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1 Answers1

0

According to the manual, the default scaling is dB. In case of zero values in the calculated spectrogram, evaluation of the logarithmic scale will lead to an error.

Gideon Kogan
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