找到最接近峰值的最小值

Question

我正在使用 scipy.singal.find_peaks 来查找峰值和最小值：

import numpy as np
from scipy.signal import find_peaks

x=np.array([9.8,57.,53.,37.,24.,19.,16.,15.,13.,13.,12.,12.,11.,11.,11.,11.,11.,11.,10.,13.,13.,13.,15.,13.,12.,14.,15.,14.,51.,34.,24.,20.,24.,22.,18.,57.,63.,38.,27.,28.,31.,33.,94.,71.,48.,40.,43.,39.,31.,27.,22.,21.,20.,19.,18.,18.,19.,20.,20.,49.,62.,48.,43.,34.,33.,28.,26.,26.,24.,23.,23.,26.,27.,70.,97.,57.,46.,68.,82.,59.,49.,37.,40.,45.,36.,33.,28.,22.,23.,284.,524.,169.,111.,148.,98.,68.,50.,38.,30.,28.])
peaks, _ = find_peaks(x)
mins, _ =find_peaks(x*-1)

看起来像：

现在我有兴趣找到最接近每个峰的最小值。所以我可以区分它们。

查看 find_peaks 文档后，参数 peak_prominece 似乎正是我要找的。

prominences = peak_prominences(x, peaks)[0]
contour_heights = x[peaks] - prominences

然后看起来像：

检查后，peak_prominences 找到了峰值之前的最小值。对于我的应用程序，我想要最近的峰值，无论它是在前面还是在后面。

如何使用 mins 为 peak_prominence 计算定义参数 wlen。？

由于mins包含最小值的索引，我如何使用它来定义wlen？我基本上必须在最小值中找到限制每个峰值的索引（即 peaks[i]）。

是否有更好的方法仅使用 mins 和 peaks 来实现此目的？

Answer 1

Now I am interested to find the closest minima to each peak. So I can take the difference between them.

以下是您要找的吗？

closest_mins = [mins[np.argmin(np.abs(x-mins))] for x in peaks]
difference = x[peaks]-x[closest_mins]
print(difference)

[ 47.   3.   1.  37.   4.  45.  54.   3.  44.  51.  36.   8. 413.  37.]

下面是 peaks、mins 和 peaks-最近的 mins 对的图，用虚线表示。请注意，有 mins 最接近多个 peaks.

plt.plot(x)
plt.plot(peaks, x[peaks],'o', label = 'peaks')
plt.plot(mins, x[mins],'s', label = 'mins')
plt.plot(closest_mins, x[closest_mins],'*', label = 'closest mins')

for p, m in zip(peaks, closest_mins):
    plt.plot([p,m], [x[p], x[m]], 'k', dashes = (4,1))
plt.legend();

找到最接近峰值的最小值

Find Closest Minima to Peak

python

signal-processing

scipy