python -在log10警告中遇到谱图除以零

Question

我尝试在这里为我的数据集中的每个轴生成一个谱图

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()

但是它给出了以下警告

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

数据集头(患者编号、时间/毫秒、x轴、y轴、z轴、标签)

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