使用 find_peaks 寻找局部最大值

Question

我正在使用 scipy.signal.find_peaks 来尝试找到非常波动的数据的最大值。使用以下数据框：

import pandas as pd
import numpy as np
from scipy.signal import find_peaks
Data = [95,95,95,95,95,95,95,95,94,94,94,94,94,94,94,94,229,444,457,387,280,188,236,181,183,183,185,186,189,190,190,190,179,165,151,151,161,214,213,213,214,213,212,195,179,160,158,155,114,98,164,346,229,39,134,149,194,1,153,171,187,185,104,102,100,90,90,92,92,92,93,93,93,93,93,93,94,94,94,94,94,11,1,11,11,70,182,104,58,60,134,115,99,97,99,98,98,97,97,97,97,97,97,97,97,97,96,96,96,96,96,96,96,96,96,96,96,96,95,95,95,95,95,95,95,95,95,95,95,95,95,95,95,95,95,95,95,95,94,94,94,94,94,94,94,94,94,94,94,94,94,94,94,93,93,152,206,221,286,326,341,360,377,391,392,393,393,393,394,406,418,420,422,422,408,389,345,329,276,224,166,113,-6,91,91,91,442,324,387,389,387,443,393,393,393,393,391,381,379,377,303,174,131,0,115,112,112,111,111,109,107,106,104,104,103,102,101,101,101,101,100,100,1,1,12,13,65,138,87]
df2 = pd.DataFrame(Data)


#convert to 1D array
number_column = df.loc[:,'Data']
numbers = number_column.values

#finding peaks for 1D array
peaks = find_peaks(numbers, height = 300, threshold = 1, distance = 5)
height = peaks[1]['peak_heights'] #list of heights of peaks
peak_pos = numbers[peaks[0]]
print(peaks)

#plot the peaks
fig = plt.figure()
ax = fig.subplots()
ax.plot(numbers)
ax.scatter(peak_pos, height,color = 'r', s = 25, label = 'Maxima')
ax.legend

我得到局部极值 457、346、442、443。然而，在这个系统中，我需要获得以下值作为极值：(457、346、422、443)

在绘制我的极值时，我得到了这个：

所以我的问题是有人知道如何获得我需要的正确极值吗？我只是缺少 422 值并且一直在尝试设置但没有成功。

Answer 1

您应该将行 peak_pos = numbers[peaks[0]] 更改为 peak_pos = peaks[0] 因为 peaks[0] 为您提供了峰的索引，这是您想要的实际 x 坐标传递给 ax.scatter.

要在 422 处获得峰值，我们可以将阈值设置为 None（这样您就不会受到与邻居的垂直距离的限制），并使距离更大，例如 10。

然后您可以将高度添加为文本注释：

import pandas as pd
import numpy as np
from scipy.signal import find_peaks
import matplotlib.pyplot as plt

Data = [95,95,95,95,95,95,95,95,94,94,94,94,94,94,94,94,229,444,457,387,280,188,236,181,183,183,185,186,189,190,190,190,179,165,151,151,161,214,213,213,214,213,212,195,179,160,158,155,114,98,164,346,229,39,134,149,194,1,153,171,187,185,104,102,100,90,90,92,92,92,93,93,93,93,93,93,94,94,94,94,94,11,1,11,11,70,182,104,58,60,134,115,99,97,99,98,98,97,97,97,97,97,97,97,97,97,96,96,96,96,96,96,96,96,96,96,96,96,95,95,95,95,95,95,95,95,95,95,95,95,95,95,95,95,95,95,95,95,94,94,94,94,94,94,94,94,94,94,94,94,94,94,94,93,93,152,206,221,286,326,341,360,377,391,392,393,393,393,394,406,418,420,422,422,408,389,345,329,276,224,166,113,-6,91,91,91,442,324,387,389,387,443,393,393,393,393,391,381,379,377,303,174,131,0,115,112,112,111,111,109,107,106,104,104,103,102,101,101,101,101,100,100,1,1,12,13,65,138,87]
df = pd.DataFrame({'Data':Data})

# convert to 1D array
number_column = df.loc[:,'Data']
numbers = number_column.values

#finding peaks for 1D array
# peaks = find_peaks(numbers, height = 300, threshold = 1, distance = 5)

peaks = find_peaks(numbers, height = 300, threshold = None, distance=10)
height = peaks[1]['peak_heights'] #list of heights of peaks
peak_pos = peaks[0]
print(peaks)

# plot the peaks
fig = plt.figure()
ax = fig.subplots()
ax.plot(numbers)
ax.scatter(peak_pos, height,color = 'r', s = 25, label = 'Maxima')
ax.legend

## add numbers as text annotations
for i, text in enumerate(height):
    if text.is_integer():
        ax.annotate(int(text), (peak_pos[i], height[i]), size=10)
    else:
        ax.annotate(text, (peak_pos[i], height[i]), size=10)
plt.show()

使用 find_peaks 寻找局部最大值

Finding local maxima using find_peaks

python

pandas

scipy

maxima