http://www.sohu.com/a/276740279_505915
x = np.array([1,2,4,5,6,9])(ca, cd) = pywt.dwt(x, "haar") #ca 低频率，粗信号 ， cd 高频，细粒度信号cat = pywt.threshold(ca, np.std(ca), mode="soft") #此处软阈值函数内容：soft=max(0,ca-np.std(ca))
https://blog.csdn.net/u010159842/article/details/52703416
