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28 lines
660 B
Python
28 lines
660 B
Python
import numpy as np
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class IIR(object):
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def __init__(self, b, a):
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self.b = np.array(b) / a[0]
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self.a = np.array(a[1:]) / a[0]
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self.x_state = [0] * len(self.b)
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self.y_state = [0] * (len(self.a) + 1)
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def __call__(self, x):
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x_, y_ = self.x_state, self.y_state
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for v in x:
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x_ = [v] + x_[:-1]
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y_ = y_[:-1]
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num = np.dot(x_, self.b)
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den = np.dot(y_, self.a)
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y = num - den
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y_ = [y] + y_
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yield y
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self.x_state, self.y_state = x_, y_
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def lfilter(b, a, x):
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f = IIR(b=b, a=a)
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y = list(f(x))
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return np.array(y)
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