python滤波器 lfilter和filtfilt 对比与应用 基于Butterworth Filter_filtfilt和lfilter

• lfilter可以用于在线数据的滤波
• 之前笔记的filtfilt用于离线数据，不会有相位差
  （可参考之前笔记：Butterworth Filter 巴特沃斯滤波器的python代码应用）

Code

# initial filter param  
def init_filter(self, order, cutoff, fs):
	wn = 2.0*cutoff/fs
	self._b, self._a = sig.butter(order, wn, 'lowpass', analog = False)
	self._dss = sig.lfilter_zi(self._b, self._a)

def lfilter_filter(self, f_x, f_y, f_z):

    f = [f_x, f_y, f_z]
    res = [0,0,0]

    for i in range (0,3):
        res[i], self._dss[i] = sig.lfilter(self._b, self._a, [f[i]], zi=self._dss[i])

    return res[0][0], res[1][0], res[2][0]    
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Plot

init_filter(order=3, cutoff=4, fs=100)

init_filter(order=3, cutoff=6, fs=100)

Ref

一些文字：在scipy.signal中应用过滤器：使用lfilter还是filtfilt？
一些代码：scipy中 filtfilt和lfilter 区别