[英]Python: 1d array circular convolution
I wonder if there's a function in numpy/scipy for 1d array circular convolution.我想知道 numpy/scipy 中是否有用于一维数组循环卷积的函数。 The scipy.signal.convolve()
function only provides "mode" but not "boundary", while the signal.convolve2d()
function needs 2d array as input. scipy.signal.convolve()
函数只提供“模式”而不提供“边界”,而signal.convolve2d()
函数需要二维数组作为输入。
I need to do this to compare open vs circular convolution as part of a time series homework.我需要这样做来比较开放与循环卷积作为时间序列作业的一部分。
By convolution theorem, you can use Fourier Transform to get circular convolution.根据卷积定理,可以使用傅立叶变换得到循环卷积。
import numpy as np
def conv_circ( signal, ker ):
'''
signal: real 1D array
ker: real 1D array
signal and ker must have same shape
'''
return np.real(np.fft.ifft( np.fft.fft(signal)*np.fft.fft(ker) ))
Since this is for homework, I'm leaving out a few details.由于这是家庭作业,我省略了一些细节。
By the definition of convolution , if you append a signal a to itself, then the convolution between aa and b will contain inside the cyclic convolution of a and b .通过卷积的定义,如果追加的信号给自己,然后AA和B之间的卷积将包含a和b的循环卷积内。
Eg, consider the following:例如,请考虑以下事项:
import numpy as np
from scipy import signal
%pylab inline
a = np.array([1] * 10)
b = np.array([1] * 10)
plot(signal.convolve(a, b));
That is the standard convolution.那就是标准的卷积。 Now this, however然而现在这
plot(signal.convolve(a, np.concatenate((b, b))));
In this last figure, try to see where is the result of the circular convolution, and how to generalize this.在最后一张图中,试着看看循环卷积的结果在哪里,以及如何推广它。
Code for this that you can copy-paste, in the spirit of StackOverflow:本着 StackOverflow 的精神,您可以复制粘贴此代码:
n = a.shape[0]
np.convolve(np.tile(a, 2), b)[n:2 * n]
This assumes that a, b have the same shape.这假设 a, b 具有相同的形状。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.